Stoichiometry Lab

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Data & Analysis Sheet

Name: Matthew Woods

 

Part 1: Vinegar reacting with calcium carbonate in eggshells

1. Describe what you saw each time you stirred the mixtures, including final observations of each.

In Cup 1, I didn’t see much just a couple bubble here and there. In Cup 2, over time I saw the egg get bigger and feels rubbery and flexible with a lot more bubbles forming than Cup 1.

2. In words only, write the chemical reaction occurring when vinegar and the eggshell react. It’s similar to Equation #7 in the instructions (but just use words, not formulas). Here’s the beginning: “Calcium carbonate plus acetic acid react to yield….”

 

Calcium Carbonate (CaCO3) and acetic acid (CH3COO) reacts in a double replacement reaction, giving you calcium acetate, water, and carbon dioxide. Since calcium acetate is soluble it’ll dissolve. This leaves behind the egg’s inner membrane, making it flexible and rubbery. 

 

3. What gas is in the bubbles produced? carbon dioxide gas

 

4. In Cup 1, what is the limiting reactant and what evidence do you have to support your claim?

 

5. In Cup 2, what is the limiting reactant and what evidence do you have to support your claim?

 

 

Part 2: Experimental Data for Baking Soda and vinegar reacting

  Data
Mass baking soda (alone) 5.0 g
Mass of beaker (alone) 15.9 g
Vinegar % 5%
Mass vinegar + beaker 59.6 g
Mass vinegar (alone) 43.7 g
Mass mixture + beaker after reaction 63.0 g
Mass mixture (only) after reaction 47.1 g

 

Part 2: Table for Calculation Results (Show work below this table and enter final results here)

  Results
6. Molar mass of sodium bicarbonate 84.0 g/mol
7. Moles of sodium bicarbonate  
8. Mass of acetic acid in vinegar  
9. Molar mass of acetic acid  
10. Moles of acetic acid  
11. Total initial mass of reactants  
12. Final mass of mixture  
13. Difference in mass = initial mass – final mass = carbon dioxide produced (actual yield)  
14. Limiting Reactant  
15. Theoretical yield carbon

dioxide

  
16. % yield carbon dioxide  

 

Be careful of sig fig in your measurements and calculations.

 

Calculations (Show all work by each question below and then enter the final results of each calculation into the table above.) Please make your answers stand out by bolding or coloring them.

 

6. Determine the molar mass of sodium bicarbonate.

Molar mass of NaHCO3 = 84.00661 g/mol

22.989770+1.00794+12.0107+15.9994*3

Sig figs = 84.0 g/mol

7. Calculate the number of moles of sodium bicarbonate using the mass of baking soda.

 

8. Determine the mass of acetic acid used in the experiment. You need to look on your bottle of vinegar to do this. If your vinegar is 4 %, this means that every 100 g of vinegar contains 4 g of acetic acid. (If it is 5 %, then 100 g contains 5 g of acetic acid). To calculate the mass of acetic acid, use the following equation. For 5 %, replace 0.04 with 0.050. Record results in table. You can assume the percent has 2 sig figs.

mass of acetic acid = mass of vinegar x 0.040

 

9. Determine the molar mass of acetic acid, HC2H3O2.

 

10. Determine the number of moles of acetic acid in each sample of vinegar. Hint: you need to use the mass of acetic acid, not the mass of vinegar.

 

11. Add the mass of baking soda and vinegar initially. This is the total initial mass of reactants.

 

12. Record the final mass of mixture.

 

13. Determine the total mass gain or loss for the reaction by comparing your initial mass to the final mass of mixture. This is the mass of carbon dioxide lost which is your actual loss.

 

14. Compare the moles of sodium bicarbonate to moles of acetic acid. Which one is the limiting reactant and why? Show calculations to support this but also describe what you saw that supports your statement.

 

15. Determine the number of grams of carbon dioxide that the reaction should theoretically produce. This is where the pen and paper stoichiometry comes in. In the calculation, use the limiting reactant as your “known” and the carbon dioxide as your unknown. You have already calculated the moles of sodium bicarbonate and acetic acid used so Step I in the “three steps process” used to go from grams known to grams unknown is already done. See the Ch. 8 Lecture about Steps II and III, remembering that one mole of acetic acid or sodium bicarbonate should produce one mole of carbon dioxide (from Eq #7).

 

16. Calculate the “percent yield” for the carbon dioxide produced. If the actual yield is a negative number, then the % yield would be 0.

 

Be careful of sig figs in your calculations. Make sure you showed work.

 

Questions

17. Look at the percent yield of carbon dioxide produced. Give a possible cause (experimental error, not calculation or measurement or instrumental error) for differences between what you calculated should be produced (theoretical yield) and what was actually produced. This should be something that you probably couldn’t avoid very well. (So don’t say, “I measured wrong” or “I calculated wrong” because this is easily avoidable by redoing the lab or re-measuring).

 

18. In the calculation for #15, why couldn’t the moles of the other reactant be used in the calculation?

 

19. True or False: After you figure out the moles of the reactants in a reaction, the lower amount of moles is always the limiting reactant. Please explain your answer thoroughly. Providing an example would be very helpful.

 

Keep going on the next page

 

Extension with calcium carbonate :

Suppose we did the quantitative experiment part 2 with calcium carbonate (found in egg shells and Tums) instead of baking soda. So we reacted it with vinegar and took mass measurements.

 

20. Write a balanced reaction for acetic acid reacting with calcium carbonate. Be careful. It is no longer a 1:1 ratio. Hint: you should’ve written this in words in #2 so now turn those words into correct formulas and balance. Include phases.

 

21. Suppose we got the following data from doing the lab with vinegar and calcium carbonate. Fill in the 2 missing boxes (with the green stars **) using the given data.

 

Data Table Run #1
Mass calcium carbonate (alone) 3.9 g
Mass beaker 30.0 g
Vinegar percent 5%
Mass vinegar + beaker 84.2 g
Mass vinegar (alone) **
Mass mixture + beaker after reaction 87.4 g
Mass mixture (only) after reaction **

 

 

Calculations (Show all work by each question below the table and then enter the final results of each calculation into the following table)

 

Results (show work below) Run #1
22. Molar mass of calcium carbonate  
23. Moles of calcium carbonate  
24. Mass of acetic acid in vinegar  
25. Molar mass of acetic acid  
26. Moles of acetic acid  
27. Total initial mass  
28. Final mass mixture (measured in lab – copy from above table)  
29. Difference in mass = initial mass – final mass = carbon dioxide produced (actual yield)  
30. Limiting Reactant  
31. Theoretical yield carbon

dioxide

  
32. % yield carbon dioxide  

 

 

22. Determine the molar mass of calcium carbonate (using a periodic table).

 

23. Calculate the number of moles of calcium carbonate using the data above.

 

24. Determine the mass of acetic acid used in the experiment. Assume vinegar is 5% on the bottle. (If it is 5 %, then 100 g contains 5 g of acetic acid). Record results in table below. You can assume the percent has 2 sig figs.

 

25. Determine the molar mass of acetic acid, HC2H3O2. No need to show work here if you did above. Just put it in the table.

 

26. Determine the number of moles of acetic acid in the sample of vinegar that was used. Hint: you need to use the mass of acetic acid, not the mass of vinegar.

 

27. Add the mass of calcium carbonate and vinegar initially. This is the total initial mass of mixture. Record results.

 

28. The final mass of the mixture is given in the table above. Just report this number below (no work to show).

 

29. Determine the total mass gain or loss for the reaction by comparing your initial mass to the final mass of mixture. This is the mass of carbon dioxide lost which is your actual loss.

 

30. To determine the number of grams of carbon dioxide that the reaction should theoretically be produced, we need to first determine the limiting reactant. This is where the pen and paper stoichiometry comes in. Compare the moles of calcium carbonate to acetic acid. Which one is the limiting reactant and why? ** Be very careful** This is not a 1:1 ratio like the first part of the lab.

 

31. Determine the theoretical yield of carbon dioxide. To do this, in the calculation, use the limiting reactant as your known and the carbon dioxide as your unknown. You have already calculated the moles of calcium carbonate and acetic acid used so Step I in the “three steps process” used to go from grams known to grams unknown is already done. See the Ch. 8 Lecture about Steps II and III, but remember that now we do not have a 1:1 ratio.

 

32. Calculate the “percent yield” for the carbon dioxide produced. If the actual yield is a negative number, then the % yield would be 0.

 

 

Extra Credit Questions:

a) In this particular example, the change in mass during the reaction provides evidence that a chemical reaction is taking place. Explain this.

 

b) Is it necessary to have a change in mass in order to have a chemical reaction? Why or why not?

 

c) Provide an example of a chemical reaction (not just a physical change) where no mass change would be observed.

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LAB 5 CHEM

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Module 5 Lab 3 Rubric

Due to issues with this lab, only do “Part 1. b. Watch the Tutorials” and “Part 1. c.  Cobalt Chloride and LeChatliers Principle Lab .”

When doing “Part 1. c.”, click on the words “Cobalt Lab” (on the right side just above WorkBench 1) which will have some directions. After following the directions given there, create a Word document where you will answer the following 4 items:

Consider the chemical reaction: Co(H  2O)  6  2+(aq) + 4Cl  -(aq) <==> CoCl  4  2-(aq) + 6H  2O(l)

1. Predict the effect of removing chloride ions. In which direction will the above reaction shift?

2. Predict the effect of adding HCl. In which direction will the above reaction shift?

3. Is the reaction endothermic or exothermic?

4. The environmental temperature for this lab is 25   oC. Calculate the K value (equilibrium constant) at this temperature as well as the K value at any other temperature of your choosing between 0 and 100    0C. Report this new K value and at what temperature it was found.

Submit the Word document for Module 5 Lab 3. Each item is worth 6 points.

 

Module 05 Lab 03 – Equilibrium Simulation

Instructions for Virtual Lab: Record all observations and take screenshots of your work.

Go to lab page:  http://chemcollective.org/equilib

1. LeChatiler’s Principle

a. Chemical Equillibrium Concept Test (Take Screen shots of answers)

b. Watch the Tutorials

i. Concentration

ii. LeChatlier’s Principle

iii. Using LeChatliers Principle

iv. Reversible Reactions

v. Temperature

vi. Volume/Presure

c. Cobalt Chloride and LeChatiliers Principle Lab

2. Process of Reaction

a. Process of Reaction Concept Test (Take Screen shots of answers)

3. Under Equilibrium Calculations

a. Chemical Equilibrium Test (Take Screen shots of answers)

4. Common Ion Effect

a. Solubility and common Ion Effect

Submit a zip file of all screenshots for this lab activit

 

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Chemistry Lab

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Engineering a Better Airbag Student Name Date

Data

Data Table 1: Model Air Bag

 

Activity Data and Calculations
Volume of 6 × 9 inch bag 1.20 L
Room temperature (in K)  
Room pressure (in atm)  
Moles of CO2 required to inflate bag at room temperature and pressure  
Balanced equation for the reaction of NaHCO3 and CH3COOH  
Mass of NaHCO3 needed for the reaction  
Volume of vinegar required

(0.833 M acetic acid)

  

 

 

 

Data Table 2: Model Air Bag

 

Trial # NaHCO3

(grams)

 Vinegar

(mL)

 Observations
1      
2      
3      

 

 

Data Table 3: 80-L Driver-Side Air Bag

 

Activity Calculations
Moles of CO2 required to inflate 80-L driver-side air bag at room temperature and pressure  
Balanced equation for the reaction of NaHCO3 and CH3COOH  
Grams of NaHCO3 needed for the reaction  
mL of CH3COOH (0.833 M) needed for the reaction  

 

Data Table 4: 160-L Front Passenger-Side Air Bag

 

Activity Calculations
Moles of CO2 required to inflate 160-L front passenger-side air bag at room temperature and pressure  
Balanced equation for the reaction of NaHCO3 and CH3COOH  
Grams of NaHCO3 needed for the reaction  
mL of CH3COOH (0.833 M) needed for the reaction  

 

 

1. Based upon the observed performance of the air bag models and the amounts of sodium bicarbonate and acetic acid (vinegar) needed for an automotive air bag of 80 or 160 L, are these reactants a good substitute for sodium azide? One additional note regarding sodium azide: the rate of inflation after a triggering impact is 40 milliseconds (0.04 s).

K:\CPMI\Distance Learning Team\DL team Images\Distance Learning Logo.jpg

© 2016 Carolina Biological Supply Company

 

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Chemistry; calculating the concentration & moles of solutions.

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Just a coupe of uni level chem questions! If you have any issues especially in the second one, read the uploaded document to get an idea.

 

Question 1 – iodine solution standardisation:

a) Calculate the mean (average) volume of the titre values you have chosen. Justify any exclusions you have made. [Average is found to be: 0.74 Litres]

b) What is the number of moles of Vitamin C present in the 25.00mL you pipette into each conical flask?

c) Using the balanced Equation C6H8O6 + I2 = C6H6O6 + 2I- + 2H+ , how many moles of iodine, I2, must have been present in the amount of iodine solution you titrated?

d) Given this number of moles and the average titre value, what is the concentration of your iodine solution?

 

Question 2 – Apple juice investigation

a) Calculate the number of moles of iodine, I2, that was involved during the redox reaction. (Hint: you are calculating n because you know c and V. What equation should you use? [n = CxV]

b) The equation for the redox reaction between iodine and Vitamin C is provided again below. Using this balanced equation, how many moles of ascorbic acid (Vitamin C) in the apple juice reacted with the I2 on average in each titration? C6H8O6 + I2 = C6H6O6 + 2I– + 2H+

c) Given the number of moles of ascorbic acid and original pipette volume, what is the concentration of Vitamin C in the apple juice you tested?

d) The concentration you calculated in Part c) is in mol.L-1 . Convert your concentration from Part c) to g.L-1 (hint: What equation relates number of moles and mass?)

e) Convert the concentration from Part d) to milligrams per litre (mg.L-1 )

f) Now convert the concentration from Part e) to milligrams per 100 ml.

g) How does your experimentally determined Vitamin C concentration compare with the value given on the juice bottle?

h) List the experimental errors that could lead to a discrepancy between the determined and the advertised value.

i) Considering your experimentally determined value and the possible sources of error, make a comment about the accuracy of the advertised amount of Vitamin C present.

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Experiment 4 Assignment – Chemistry

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Name:__________________

College Chemistry I – Chem. 1806

Lab Report 4 assignment

 

1. Complete the following table. (10 points)

Data Table 1
Initial: CaCl2∙2H2O (g) Click or tap here to enter text.
Initial: CaCl2∙2H2O (moles) Click or tap here to enter text.
Initial: CaCl2 (moles) Click or tap here to enter text.
Initial: Na2CO3 (moles) Click or tap here to enter text.
Initial: Na2CO3 (g) Click or tap here to enter text.
Theoretical: CaCO3 (g) Click or tap here to enter text.
Mass of Filter Paper (g) Click or tap here to enter text.
Mass of Filter Paper + CaCO3 (g) Click or tap here to enter text.
Actual: CaCO3 (g) Click or tap here to enter text.
% Yield Click or tap here to enter text.

 

2. A perfect percent yield would be 100%. Based on your results, describe your degree of accuracy. (5 points)

Click or tap here to enter text.

 

3. Describe how conservation of mass could be checked in the experiment performed. (5 points)

Click or tap here to enter text.

 

4. Determine the quantity of pure CaCl2 in 7.5 g of CaCl2∙9H2O. (5 points)

Click or tap here to enter text.

 

5. Is it possible to get a percent yield over 100%? Be sure to explain your reasoning behind your answer. (5 points)

Click or tap here to enter text.

 

6. Provide a written summary of your results in your own words. Be sure to explain your results and provide an explanation if anything went wrong in your experiment. (10 points)

Click or tap here to enter text.

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Chemistry

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Lab 01: Coffee Problem

Purpose of Experiment: To perform specific heat calculations and check those calculations using the virtual lab example.

Deliverables:

· A screenshot of the correct answer and all calculations and explanations

Instructions:

For this lab assignment, you will need to read the instructions for the Metals Density Problem on the ChemCollective website. After you complete this reading, return to this assignment to read an example problem that will help you to complete the lab on the ChemCollective page.

Go to lab page:  http://chemcollective.org/activities/autograded/115

To complete the lab, all calculations and an explanation of how you will make the coffee must be shown in the provided box below the virtual lab. Once the green check box is clicked and the lab shows you have a correct answer, take a screen shot and submit the screenshot of the lab for your grade.

Lab Assistance:

The following will help you to complete out the Coffee Problem lab.

All glassware used in this lab (even the pipets) must be insulated. Once the coffee and milk are selected, you must change the temperature to the initial temperature and insulate the glassware or it will quickly lose temperature.

Hint: the coffee is in an insulated travel mug, so no heat escapes. To insulate a piece of glassware in Virtual Lab, Mac-users should command-click (or open-apple click) on the beaker or flask; Windows users should right click on the beaker or flask. From the menu that appears, choose “Thermal Properties.” Check the box labeled “insulated from surroundings.” The temperature of the solution in that beaker or flask will remain constant.

All calculations and an explanation of how you will make the coffee must be shown in the provided box below the virtual lab. Once the green check box is clicked and the lab shows you have a correct answer, take a screen shot and submit the screenshot of the lab for your grade.

Example question and calculation:

You decided to make hot water for your favorite flavored tea drink. The water, after boiling, was at about 98 ˚C when you poured it over the tea bags. You now have 100 mL hot tea at 98 ˚C and want to dilute the tea and bring it to room temperature at about 25 ˚C. To make the tea to the correct temperature, you will add a portion of cold water at a temperature of 5 ˚C. How much cold water should you add to the hot tea water? (Hint: the density of tea and water is 1 g/mL and the specific heat of tea and water is 4.184 J/g∙˚C).

First convert the volume to mass using density:

100mL⋅1g1mL=100g100mL⋅1g1mL=100g

Next, use the following equation: q=m×C×ΔTq=m×C×∆T. This problem requires an endothermic and an exothermic reaction; therefore the equation is modified: q=−qq=−q. The cold water absorbs heat and is the endothermic reaction; therefore, the cold water portion is the qq. The tea temperature being brought down is releasing heat and therefore is the −q−q side of the equation. Now we can substitute the m×C×ΔTm×C×∆T for each qq, making sure to keep the signs of each qq.

(m×C×ΔT)=−(m×C×ΔT)(m×C×∆T)=−(m×C×∆T)

(m×C×(Tf−Ti))=−(m×C×(Tf−Ti))(m×C×(Tf−Ti))=−(m×C×(Tf−Ti))

(m×4.184Jg⋅℃×(25℃−5℃))=−(100g×4.184Jg⋅℃×(25℃−98℃))(m×4.184Jg⋅℃×(25℃−5℃))=−(100g×4.184Jg⋅℃×(25℃−98℃))

(m×4.184Jg⋅℃×(20℃))=−(100g×4.184Jg⋅℃×(−73℃))(m×4.184Jg⋅℃×(20℃))=−(100g×4.184Jg⋅℃×(−73℃))

(m×83.68Jg)=−(−30,543.2J)(m×83.68Jg)=−(−30,543.2J)

(m×83.68Jg)=30,543.2J(m×83.68Jg)=30,543.2J

m=30,543.2J83.68Jg=365gm=30,543.2J83.68Jg=365g

Convert the grams into mL with the density: 365g×1mL1g=365mL365g×1mL1g=365mL

Once you have completed the calculation, check you work by doing the virtual lab as explained.

 

 

Lab 2 Powerade

To access your lab, please follow these instructions— *if you have already done steps 1-10, simply log in to view your course and participate in lab activities:

1. Please go to:  https://oli.cmu.edu/jcourse/webui/register/student.do 

2. This will bring you to the “Course Key Students” page.

3. Enter the Course Key “GRC19” in the box and click “register.”

4. Create an account by filling in the information (be sure to use an account ID and password you will remember and make a note of it for future logins).

5. Click “I’m not a robot” and “Sign Up.”

6. Confirm your account by clicking on “confirm account.”

7. Read the consent form, then agree by choosing “I agree” and “submit.”

8. Click on “Register” for the Chemistry Virtual Lab Activities with Instructor Sandra Raysor.

9. Click on “Enter course” next to the red arrow to begin the lab.

10. Find the lab required for the assignment and begin work.

Should you experience issues, please contact the PSC at 1-866-693-2211 and let them know you need assistance with labs in the CHM1100 course.

Purpose of Experiment: To modify the concentration of liquids.

All of the instructions for this lab are located within ChemCollective. You will step through this lab completing different tasks on different pages. At the end of each task, you will see a “Correct” or “Incorrect” screen. You are able to try again if you see an “Incorrect” screen. Be sure to take a screenshot of each “Correct” screen. Submit a zip file of all screenshots for this lab activity.

 

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GLOBAL SIMULATION CHALLENGE

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THE ASSIGNMENT

(GENERAL INFORMATION)

PLEASE IN THE GLOBAL SIMULATION CHALLENGE, IT’S LIKE A GAME WITH DIFFERENT ROUNDS, IT HAS ROUND 1 TO 7, AND EACH ROUNDS ARE BEEN PLAY SEPARATE AND HAS DIFFERENT OUTCOME IN EACH, IN THE GAME THE COMPANYS HEADQUATERS ARE TO BE USA WHILE ITS SUBSIDARIES ARE EUROPE AND ASIA, so only three location is in this game.

 

IN THE GAME THERE ARE MANY GROUP OF PEOPLES, GROUP INTO 4 TO 5 GROUPS IN ORDER TO MAKEUP AND CREATE DIFFERENT COMPANIES IN THE TECHONLOGY INDUSTRY. IN THIS INDUSTRY MY GROUP AND COMPANY NAME IS GAGA COMPANY AND IN THE GAME THERE ARE FOUR PRODUCTS AVAILABLE FOR EACH GROUP AND TEAM TO BASE THERE PRODUCTION AND DECISIONS ON. AND THOSE PRODUCTS ARE IDENTIFY AS TECH 1, TECH 2, TECH 3 AND TECH 4.

HOWEVER GAGA COMPANY CHOSE ONLY TO BASE ITS PRODUCTIONS AND DECISION ON PRODUCT TECH 1, TECH 2 AND TECH4 ONLY BECAUSE OF THERE HIGH RATE OF DAMANDS AND GROW IN THE INDUSTRY.

 

PART 1 ( HAS 2 QUS)

1.    A critical evaluation of the Global Simulation Challenge and how it could be improved.  (500 WORDS)

 

2.    A signed letter outlining how the marks should be split. This gives the team an opportunity to reward outstanding contribution or lack thereof. Any additional marks will reduce the team mark. (200 WORDS)

 

EACH TEAM MEMBER WILL BE AWARDED EQUAILLY DUE TO EQUAL PERPORMANCE FROM EACH TEAM MEMBER SO EACH TEAM MEMBER WILL BE REWARD 25% OF THE MARK. FOUR TEAM MEMBER 25% EACH WHICH MAKE IT TOTAL OF 100% MARK

 

 

 

 

 

 

 

PART 2

  Individual report  (3 QUS)      (1500 words)

 

1.     An individual reflection of the round(s) for which you had lead responsibility, to include; legacy, communication, agreement, leading the team, finalizing/agreeing the decisions and analysis of the results.

 

2.    In depth reflection of the simulation structure and rules, Business Strategy lectures and theory, analysis of the results and the extent to which they informed each other.

 

3.    A report on the usefulness of the Global Challenge simulation and how it helped you understand the broader concepts of Business strategy and Business in general.

 

ADDTION INFORMATION THE WILL BE USEFULL FOR PART 2 ANSWERS

Gaga company have the biggest market share in USA in all the ROUNDS 1-7 and the biggest profit in EROUPE and in ASIA gaga company is in third position both in market share and profit.

FROM ROUND 1-5 gaga company mostly base it production and performance on TECH 1 and TECH 2.

FROM ROUND 6-7 the company mostly base on TECH 1, TECH 2 and TECH 4

 

 

INFORMATION ON THE STRATEGY

·         MARKET STRATEGY GAGA GROUP USE IS-

High advertisement in use US, price strategy in ASIA by using medium price level to attract  more market AND In EUROPE we maintain high Tech in the market and high research and development strategy in order to improve product quality and maintain best quality products in the market.

 

·         HUMAN RESOURCE MANAGEMENT-

Gaga group always try to add and increase salary in each and every ROUND from ROUND 1 TO ROUND 7 by $50 increase

 

·         PRODUCTION STRATEGY-

Team Gaga try to maintain lower cost of production and high utilisation of capacity and resource and also have more production plants in ASIA because of Asia low cost of labour and production in order to maintain lower production cost generally.

 

·         Logistic-

Gaga group try to avoid transportation and reallocation of products between USA and ASIA because of high tax and tariff between the two countries.

 

·         FINANCE-

Gaga team always pay back long term debt as soon as possible in order to avoid high interest rate.

 

And more DIVIDEND payment was made especially on the last TWO ROUNDS

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chemistry

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Nuclear Chemistry

 

Pre-Lab Questions

1. Define radioactivity decay.

The spontaneous transformation of an unstable atomic nucleus into a lighter one, in which radiation is released in the form of alpha particles, beta particles, gamma rays, and other particles.

2. What is predictable about radioactive decay? What is unpredictable?

What is predictable about radioactive decay is how long it will take for the half-life of the mass of the material to decay. What is unpredictable about radioactive decay is that it is random and spontaneous and how long a particular molecule takes to decay.

3. Describe how half-life is used to determine the geologic age of a rock.

To determine the age of a rock, measure the ratio of the remaining parent atom to the amount of daughter atom and by this you will know how long the molecule has been decaying.

 

 

 

Table 2: Radioactive Decay Data

Trial Skittles® “S” Up (Parent Atoms) Skittles® “S” Down (Daughter Atoms) for each Trial Skittles® “S” Down (Daughter Atoms) Cumulative Total
0 61  0  0 
1 30  31  31 
2 7  23  54 
3 3  4  58 
4 2  1  59 
5 1  1  60
6  1  0 60 
7 0   1 61 

 

Post-Lab Questions

1. Create a graph using your data from Table 2 and a computer program such as Microsoft Excel®. If you do not have a graphing program installed on your computer, you can access one on the internet via the following links: http://nces.ed.gov/nceskids/createagraph/ or http://www.onlinecharttool.com. On the x-axis plot “Trial Number.” On the y-axis plot “Parent Atoms” and “Total Daughter Atoms.”

 

 

 

 

2. Suppose the isotope your Skittles® represented was uranium-238 and the trials represent the number of half-lives. How old was the sample at the end of your tests? Use Table 1 in the Introduction to help you answer this question. Include your calculations.

4.5 x 7 = 31.5 billion years’ old

 

3. Suppose the isotope your Skittles® represented was uranium-238 and the trials represent the number of half-lives. Use the ratio of daughter to parent atoms to calculate the age of the sample in Trial 3. Use Table 1 in the Introduction to help you answer this question. Include your calculations.

Ratio: 1:127

(7)(4.5) = 31.5 billion years old

 

4. Suppose the isotope your Skittles® represented was uranium-238 and the trials represent the number of half-lives. Calculate the age of the sample after three half-lives. (Hint: this calculation should be different than Question 2). Does this match your answer to Question 3? Why or why not? Use Table 1 in the introduction to help you answer this question. Include your calculations.

 

 

5. Identify and describe similarities and differences between this experiment and radioactive decay in nature.

Shows half life but not time.

 

Trial 5 Trial 7

Radioactive Decay

Parent Atoms 0 1 2 3 4 5 6 7 61 30 7 3 2 1 1 0 Total Daughter Atoms 0 1 2 3 4 5 6 7 0 31 54 58 59 60 60 61

Trials

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Module 3 Lab Experiment-Chimestry

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Name:__________________

College Chemistry I – Chem. 1806

Lab Report 3 assignment

 

Naming Chemical Compounds

1. Name the following elements, binary ionic compounds, and polyatomic ions using the rules that have been discussed. (5 points)

Data Table 1
  Item to name Name
1 S Click or tap here to enter text.
2 Sb Click or tap here to enter text.
3 N2 Click or tap here to enter text.
4 PO43- Click or tap here to enter text.
5 Au Click or tap here to enter text.
6 Rb Click or tap here to enter text.
7 LiCl Click or tap here to enter text.
8 AlBr3 Click or tap here to enter text.
9 KMnO4 Click or tap here to enter text.
10 Cu(OH)2 Click or tap here to enter text.
11 FeSO4 Click or tap here to enter text.
12 NH4Cl Click or tap here to enter text.
13 ZnCO3 Click or tap here to enter text.
14 SnF2 Click or tap here to enter text.
15 MgSO4 Click or tap here to enter text.
16 MnO2 Click or tap here to enter text.
17 Ca3(PO4)2 Click or tap here to enter text.
18 NaOH Click or tap here to enter text.
19 HCl Click or tap here to enter text.
20 Ba(HSO3)2 Click or tap here to enter text.
21 HNO3 Click or tap here to enter text.
22 FeSO3 Click or tap here to enter text.
23 Al2S3 Click or tap here to enter text.
24 KNO3 Click or tap here to enter text.

 

 

2. Write the formula of the following compounds using the rules that have been discussed. (5 points)

Data Table 2
  Compound Name Formula
1 Potassium cyanide Click or tap here to enter text.
2 Ammonium carbonate Click or tap here to enter text.
3 Lithium selenide Click or tap here to enter text.
4 Calcium hydrogen carbonate Click or tap here to enter text.
5 Potassium carbonate Click or tap here to enter text.
6 Strontium hydroxide Click or tap here to enter text.
7 Cobalt (III) phosphate Click or tap here to enter text.
8 Iron (II) sulfide Click or tap here to enter text.
9 Zinc permanganate Click or tap here to enter text.
10 Silver nitrate Click or tap here to enter text.
11 Cadmium sulfide Click or tap here to enter text.
12 Sodium sulfide Click or tap here to enter text.
13 Barium iodide Click or tap here to enter text.
14 Lead (II) chloride Click or tap here to enter text.
15 Aluminum hydroxide Click or tap here to enter text.
16 Barium permanganate Click or tap here to enter text.
17 Lithium sulfate Click or tap here to enter text.
18 Sulfuric acid Click or tap here to enter text.
19 Magnesium chloride Click or tap here to enter text.
20 Potassium hydroxide Click or tap here to enter text.
21 Sodium sulfite Click or tap here to enter text.
22 Tin (II) fluoride Click or tap here to enter text.
23 Iron (II) chloride Click or tap here to enter text.
24 Copper (II) nitrate Click or tap here to enter text.

 

3. Write the name of the following compounds using the rules that have been discussed. Nitric oxide will not be accepted for the compound name of NO since it has not been discussed. (5 points)

Data Table 3
  Formula Compound Name
1 B2O3 Click or tap here to enter text.
2 NO Click or tap here to enter text.
3 N2O4 Click or tap here to enter text.
4 S2F10 Click or tap here to enter text.
5 BrF3 Click or tap here to enter text.
6 H2O Click or tap here to enter text.
7 SiCl4 Click or tap here to enter text.
8 H2O2 Click or tap here to enter text.
9 CO Click or tap here to enter text.
10 N2O Click or tap here to enter text.
11 SiO2 Click or tap here to enter text.
12 CCl4 Click or tap here to enter text.
13 PCl3 Click or tap here to enter text.
14 PCl5 Click or tap here to enter text.
15 SF6 Click or tap here to enter text.
16 O2F2 Click or tap here to enter text.
17 P4S3 Click or tap here to enter text.
18 XeF4 Click or tap here to enter text.

 

4. Write the formulas of the following compounds using the rules that have been discussed. (5 points)

Data Table 4
  Compound Name Formula
1 Tribromine octoxide Click or tap here to enter text.
2 Tetraiodide nonoxide Click or tap here to enter text.
3 Dihydrogen monosulfide Click or tap here to enter text.
4 Iodine monochloride Click or tap here to enter text.
5 Nitrogen monoxide Click or tap here to enter text.
6 Hydrogen monochloride Click or tap here to enter text.
7 Tricarbon dioxide Click or tap here to enter text.
8 Bromine trichloride Click or tap here to enter text.
9 Nitrogen trihydride Click or tap here to enter text.
10 Dinitrogen monosulfide Click or tap here to enter text.
11 Carbon tetrabromide Click or tap here to enter text.
12 Sulfur trioxide Click or tap here to enter text.
13 Iodine hexafluoride Click or tap here to enter text.
14 Tetraphosphorus decasulfide Click or tap here to enter text.
15 Dichlorine pentoxide Click or tap here to enter text.
16 Diphosphorus tetraiodide Click or tap here to enter text.
17 Diphosphorus pentasulfide Click or tap here to enter text.
18 Carbon dioxide Click or tap here to enter text.

 

 

Lewis Structure Model

5. Complete the following table. No pictures from the internet are allowed. The VSEPR model must be made using the model kit from your lab kit.(5 points)

Data Table 1
  Molecule or Ionic Compound Number of Valence Electrons Lewis Structure (drawn by hand) VSEPR Model (insert a picture of your model)
1 CCl4 Click or tap here to enter text.
2 MgCl2 Click or tap here to enter text.
3 AlCl3 Click or tap here to enter text.
4 PbI4 Click or tap here to enter text.
5 CH4 Click or tap here to enter text.
6 ICl5 Click or tap here to enter text.
7 CH2O Click or tap here to enter text.
8 NF3 Click or tap here to enter text.
9 H2O Click or tap here to enter text.
10 CO2 Click or tap here to enter text.
11 [NO2]- Click or tap here to enter text.
12 [NH4]+ Click or tap here to enter text.
13 SO2 Click or tap here to enter text.
14 NH3 Click or tap here to enter text.
15 H2S Click or tap here to enter text.
16 SF6 Click or tap here to enter text.
17 SbCl5 Click or tap here to enter text.

 

 

6. Complete the following table. (5 points)

Data Table 2
  Molecule Number of atoms or sets of lone pairs surrounding the central atom Structure Geometry (Name)
1 CCl4 Click or tap here to enter text. Click or tap here to enter text.
2 MgCl2 Click or tap here to enter text. Click or tap here to enter text.
3 AlCl3 Click or tap here to enter text. Click or tap here to enter text.
4 PbI4 Click or tap here to enter text. Click or tap here to enter text.
5 CH4 Click or tap here to enter text. Click or tap here to enter text.
6 ICl5 Click or tap here to enter text. Click or tap here to enter text.
7 CH2O Click or tap here to enter text. Click or tap here to enter text.
8 NF3 Click or tap here to enter text. Click or tap here to enter text.
9 H2O Click or tap here to enter text. Click or tap here to enter text.
10 CO2 Click or tap here to enter text. Click or tap here to enter text.
11 [NO2]- Click or tap here to enter text. Click or tap here to enter text.
12 [NH4]+ Click or tap here to enter text. Click or tap here to enter text.
13 SO2 Click or tap here to enter text. Click or tap here to enter text.
14 NH3 Click or tap here to enter text. Click or tap here to enter text.
15 H2S Click or tap here to enter text. Click or tap here to enter text.
16 SF6 Click or tap here to enter text. Click or tap here to enter text.
17 SbCl5 Click or tap here to enter text. Click or tap here to enter text.

 

7. Which, if any, of the molecules in Data Table 1 (Lewis Structure Model) had resonance structures? How many resonance structures did each of the molecules have? (5 points)

Click or tap here to enter text.

 

8. Lewis structures are drawn for molecules and not typically for ionic compounds. Explain why Lewis structures are not typically drawn for ionic compounds. (5 points)

 

Click or tap here to enter text.

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Chemistry lab hw

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EXPERIMENT #1: QUALITATIVE ANALYSIS OF UNKNOWN IONS IN A SOLTUION

Project:

In a vacated company laboratory, you find an unlabeled bottle of aqueous solution. It is known that the cation(s) is(are) from the following: Ag+, Hg22+, Pb2+, Cu2+, Bi3+, As3+, Co2+, Ni2+, Fe3+, and Al3+; and the anions from SO42-, CO32-, PO43-, Cl-, and NO3-. Design an experiment to identify what ion(s) is(are) present in this unlabeled solution.

· Design a detailed procedure to separate the ions into groups

· Identify the ions in the unknown solution using the information in the Background Section.

· Develop a flow chart to clearly show the steps, and add individual tests to the flow chart to show the identification. List the techniques and equipment you would need to use.

Background:

The first step in qualitative analysis is to separate the ions into groups, because many ions may give similar results when the same reagents are added, and hence may interfere with each other. If present, Ag+, Hg22+ and Pb2+ will all form white precipitate when HCl is added, thus separate from the rest of the ions in the solution. After Ag+, Hg22+, Pb2+ are removed from the solution, Cu2+, Bi3+, As3+, if present, will all form precipitate with H2S in acidic conditions , thus separate from the rest of the solution. Co2+, Ni2+, Fe3+, and Al3+, if present, will precipitate when NaOH is added, thus separate from the rest of the solution.

After separation of the ions, individual tests are to be performed to identify the ions. For example, a white precipitate forms when HCl is added to the unknown solution, indicating one, two, or all three cations from Group I (Ag+, Hg22+, Pb2+) may exist. After adding excess HCl to ensure that all of the Group I cations have precipitated out of the solution, the precipitate is collected (using which technique?), washed (using which technique?) and dried. Always keep the rest of the clear solution because you need to analyze it for other ions later! The precipitate collected is then analyzed for existence of Ag+, Hg22+ or Pb2+:

PbCl2 is soluble in hot water while AgCl and Hg2Cl2 are not. Therefore adding water the precipitate and heating the mixture will dissolve PbCl2 and separate it from AgCl and Hg2Cl2 (using which techniques?). AgCl will redissolve if NH3 is added,

AgCl(s) + 2 NH3 (aq) ⇌ Ag(NH3)2+(aq) + Cl-(aq)

but will form a white precipitate again if the solution is acidified with HNO3,

Ag(NH3)2+(aq) + Cl-(aq) + 2H+(aq) ⇌AgCl(s) (white) + 2 NH4+(aq)

This series confirms the existence of Ag+.

Hg22+ is identified by the following reaction,

Hg2Cl2(s) + 2 NH3(aq) ⇌ Hg(s) (black) + HgNH2Cl(s) (white) + NH4+(aq) + Cl-(aq)

Pb2+ is confirmed by the K2CrO4 test:

Pb2+(aq) + CrO42-(aq) ⇌ PbCrO4(s) (yellow)

After Group I cations are removed from the unknown solution, Group II cations are precipitated by adding 6M HCl and thioacetamide (CH3CSNH2) which hydrolyzes to give H2S:

CH3CSNH2(aq) + 2H2O(l) + H+(aq) ⇌ CH3COOH(aq) + NH4+(aq) + H2S(aq)

H2S will then precipitate Cu2+, Bi3+, As3+ from the solution, if they are present. Copper and bismuth sulfides are insoluble in basic thioacetamide while arsenic sulfide dissolves in the form of thio complex ion, AsS33-, thus separating arsenic from copper and bismuth.

Arsenic is tested as follows,

As2S3(s) + H2S (aq) + NaOH (aq) → AsS33-(aq)

AsS33-(aq) + HCl(aq) → As2S3(s)

As2S3(s) + H2O2 (basic) → AsO43-(aq)

AsO43-(aq) + Mg(OH)2 (magnesia mixture) → MgNH4AsO4 (s) (white)

CuS and Bi2S3 dissolve in hot HNO3 forming Cu2+ and Bi3+ ions; addition of NH3 will form a white precipitate, Bi(OH)3, with Bi3+, and a deep blue color complex solution, Cu(NH3)42+, with Cu2+.

Co2+, Ni2+, Fe3+, and Al3+ all form insoluble hydroxides when NaOH is added, but Al(OH)3 will re-dissolve if excess NaOH is added because of its amphotericity,

Al(OH)3(s) + OH-(aq) ⇌ Al(OH)4-(aq)

Therefore, Co(OH)2(s, lavender), Ni(OH)2(s, green), Fe(OH)3(s, reddish-brown) are separated from Al(OH)4-(aq). They will dissolve again if the pH is adjusted to acidic. Since the tests for these three ions, Co2+, Ni2+, Fe3+, do not interfere significantly with each other, the solution is simply divided into three portions for individual tests:

Ni2+(aq) + 6NH3(aq) ⇌ Ni(NH3)62+(aq)

Ni(NH3)62+(aq) + 2HDMG ⇌ Ni(DMG)2(s) (red) + 2NH4+(aq) + 4NH3(aq)

where HDMG is demethylglyoxime, (CH3)2C2(NOH)2.

Co2+ is tested by first adding NaF to complex with Fe3+ (FeF63-) to prevent interference from Fe3+, followed by addition of saturated NH4SCN in ethanol solution:

Co2+ + 4SCN- ⇌ Co(SCN)42-(blue)

Fe3+ is tested by adding KSCN:

Fe3+(aq) + SCN-(aq) ⇌ FeSCN2+(aq) (red)

Aluminum is tested by the following steps:

1. Al(OH)4-(aq) + 16M HNO3 → Al3+(aq)

2. Al3+(aq) + 15M NH3 → Al(OH)3(s)

3. Al(OH)3(s) + 3M CH3COOH → Al3+(aq)

4. Al3+(aq) + aluminum reagent + 6M NH3 → red precipitate (Al(OH)3-Al)

The anions are analyzed in a similar fashion. The BaCl2 group where addition of BaCl2 forms white precipitates with SO42-, CO32-, PO43-,

SO42-(aq) + Ba2+(aq) ⇌ BaSO4(s)

CO32-(aq) + Ba2+(aq) ⇌ BaCO3(s)

2PO43-(aq) + 3Ba2+(aq) ⇌ Ba3(PO4)2(s)

The difference is BaSO4(s) will not dissolve in HCl , while both BaCO3(s) and Ba3(PO4)2(s) do dissolve in HCl; BaCO3(s) also effervesce with release of CO2.

BaCO3(s) + 2H+(aq) ⇌ Ba2+(aq) + CO2(g) + H2O(l)

The AgNO3 group , where addition of AgNO3 precipitates CO32-, PO43-, and Cl-. Ag2SO4 is slightly soluble.

CO32-(aq) + 2Ag+(aq) ⇌ Ag2CO3(s) (white)

PO43-(aq) + 3Ag+(aq) ⇌ Ag3PO4(s) (yellow)

Cl-(aq) + Ag+(aq) ⇌ AgCl(s) (white)

Addition of HNO3 causes Ag2CO3 and Ag3PO4 to dissolve, with Ag2CO3 also causing effervescence, while AgCl remains as a white precipitate.

The soluble group, NO3-, is tested by the brown ring test. The addition of H2SO4 and FeSO4 causes a brown ring of Fe(H2O)5NO2+ to appear at the interface of the two layers.

NO3-(aq) + 4H+(aq) +4Fe2+(aq) + 3H2O → 3Fe3+(aq) + Fe(H2O)5NO2+(aq)

Identification of the Silver group ions: Ag+, Hg22+, and Pb2+

These ions are removed from the solution by adding excess 6M HCl to the solution and stirring with a stirring rod. After centrifugation, the precipitate will stick to the wall and bottom of the test tube and the supernatant solution will be clear. Test for complete precipitation by adding 2 more drops of 6M HCl to the clear supernatant liquid. If the solution turns cloudy, add two more drops of HCl, stir and centrifuge. Repeat until the supernatant liquid is clear when HCl is added.

Decant the supernatant solution and wash the precipitate with some cold water, centrifuge and decant the wash solution. The silver group ions, if any, are now in the precipitate.

Add some distilled water to the precipitate and place the test tube in a hot water bath, stir and heat for a few minutes. Quickly centrifuge and decant the solution in a clean test tube labeled “Pb2+”. Repeat the above step two more times and combine the solutions after centrifuging in the labeled test tube. The remaining precipitate, if any, will be analyzed for Ag+ and Hg22+.

Test for Ag+ and Hg22+: Add 20 drops of 4M NH3 to the precipitate. If a grey to black precipitate forms Hg22+ is present. Centrifuge and decant the clear liquid in a clean test tube. Acidify the solution with 4M HNO3. A white precipitate of AgCl or cloudiness confirms the presence of Ag+.

Test for Pb2+: Pour half of the solution from the Pb2+-labeled test tube into a clean test tube, add a few drops of K2CrO4 and observe; add a few drops of KI to the other portion of the solution, observe.

Identification of the Copper-Arsenic group ions: Cu2+, Bi3+, and As3+

To the clear supernatant solution after removing the silver group ions, add a few drops of 6M HCl and 20 drops of thioacetamide (CH3CSNH2) and heat in a boiling water bath for 5 minutes. Add 1 mL of H2O and heat for another 10 min. Centrifuge and decant the supernatant into a clean test tube labeled “Group II”. Group II ions (Cu2+, Bi3+, and As3+), if present, will be in the precipitate.

Wash the precipitate twice with 10 drops of 0.1M HCl, centrifuge and decant. Discard the wash solutions.

Add 15 drops of 4M NaOH and 4 drops of thioacetamide to the precipitate. Heat in a water bath for 5 min. Centrifuge and decant. Label the solution “As”. Analyze the precipitate which could be  either CuS or Bi2S3 or both.

Wash the precipitate with a mixture of 1 mL of water and 2 drops of NH4NO3, centrifuge and discard the wash solution. Add 15 drops of 6M HNO3 to the precipitate and heat in a water bath for 5 min. Stir constantly while heating. Note that free sulfur is formed. Centrifuge and discard the sulfur. Analyze the solution for copper and bismuth ions.

Test for Cu2+ and Bi3+: Make the solution basic with 15M aqueous NH3. A deep blue solution (depending on the copper ion concentration) due to complex ion, Cu(NH3)42+, proves the presence of copper ions. A white precipitate of Bi(OH)3 forms if bismuth ions are present. Centrifuge and discard the supernatant liquid. Wash the precipitate with 10 drops of hot water, centrifuge and discard the wash solutions. Add 3 drops of 6M NaOH and 2 drops of freshly prepared SnCl2 solution. A black precipitate of Bi proves the presence of bismuth ions.

Test for As3+: Acidify the As-labeled solution with 1M HCl. Heat in a water bath for several minutes. Centrifuge and discard the solution. A yellow residue could be As2S3. Add 12 drops of 4M NH3 and 6 drops of 3% H2O2 to the residue. Heat in a water bath for several min. Centrifuge and discard any residue which could be sulfur. Add 2 drops of 15M NH3 and 5 drops of magnesia mixture to the centrifuge. A white precipitate of MgNH4AsO4, which forms slowly, proves the presence of arsenic ions.

Identification of the Nickel-Aluminum group ions: Co2+, Ni2+, Fe3+ and Al3+

Get 1 mL of the clear supernatant solution labeled with “Group III” from removing Group II ions and place in a clean test tube. Add 2 mL of 6M NaOH and mix thoroughly. The color of the precipitate could give an indication of which ions are present. Add a few drops of distilled water and heat in a boiling water bath for 2 min. Cool and centrifuge. Decant the supernatant liquid which may contain Al(OH)4- into a clean test tube and label with “Al”. Wash the precipitate twice with 4 mL portions of distilled water, centrifuge after each washing and discard the wash solution.

Add 1 mL 6M H2SO4 to the washed precipitate , mix and heat in a boiling water bath for several min. Remove the test tube and dilute the solution to 3 mL using distilled water. Cool and divide the solution into 3 equal portions in 3 clean test tubes.

Test for Ni2+: To the first portion, add 15M NH3 dropwise until basic. Centrifuge if a precipitate forms. Do not decant. Add 5 drops of HDMG to the supernatant solution. A cherry red precipitate of Hi(DMG)2 proves the presence of nickel ions.

Test for Co2+: To the second portion, add a small amount of solid NaF, stir. Add additional NaF with stirring until some of the solid remains at the bottom of the test tube. Add several crystals of NH4SCN. A blue complex of Co(SCN)42- proves the presence of cobalt ions.

Test for Fe3+: To the third portion, add a few drops of KSCN solution. A blood red color proves the presence of iron ions.

Test for Al3+: Slightly acidify the supernatant solution labeled with “Al” with 16M HNO3. Add 15M NH3 until the solution is basic. Stir the solution thoroughly. Centrifuge and decant. If aluminum is present a white gelatinous precipitate will be present. Wash the precipitate three times with 10 drops of hot water, centrifuge and decant after each wash. Discard the wash solutions. Add 5 drops of 3M CH3COOH to the precipitate. Stir to dissolve the precipitate, centrifuge and decant in a clean test tube. Discard any undissolved precipitate. Add 2 drops of aluminum reagent. Stir, then make slightly basic with 6M NH3. Mix and centrifuge. A red precipitate confirms the presence of aluminum ions.

Identification of NO3-

To 1 mL of the sample solution, add 3 mL of concentrated H2SO4 and mix. Let the test tube cool to room temperature. Hold the test tube in an incline position and pour down the inner side of the test tube several mL of FeSO4 solution so that there will be two distinct layers. The formation of a brown ring at the interface of the two liquids indicates the presence of the nitrate ions.

Analysis of an Unknown

Individual Pre-lab

1. The main goal/purpose of the experiment is (what are you trying to discover in this lab):

a. What  are the questions we need to answer with the results obtained from this experiment?

b. The hypothesis(es) we seek to test in this experiment is(are) (what is the basis of your experiment, see Ch.1 in your text):

a. What tests will be used to test for the presence of unknowns cations?

b. What tests will be used to test for the  presence of unknown anions?

b. The key question the experiment seeks to answer is (what problem are you addressing?)

(see 1 a):

c. The controls involved in this experiment are (a control is used to minimize the unintended influence of other variables on the same system)

3. What is the best way to insure that there are no false positives or that there is not contamination  or interference.?

4. The key concept(s) or theory(ies) behind the experiment is(are) (define terms like pure substance, mixture, sublimation, etc. can you explain the relevant theory):

a. How can selective precipitation be used to identify unknown ions?

b. The important technique(s) used in this experiment is(are) (sublimation, etc.)  Please describe:

c. What technique is used to separate precipitate from ions that remain dissolved in the solution?

d. What technique is used to treat precipitate or solution for presence of an unknown ion?

e. The experiment is based on the following assumptions (identify your assumptions and determine if they are justifiable):

5. Discuss the importance of selective participation.  

6. The data that will be collected in the experiment are (what do you plan to record in your notebook)

a. What results will be collected and recorded in your lab notebook?

b. The potential consequences of the experiment are:

c. What can be expected if positive results are obtained?

d. What might prevent positive results from being obtained?

7. The point of view behind the experiment is (make sure it’s scientific).

8. What is this experiment designed to measure?

9. What can the results NOT tell us about the experiment?

10. What special safety precautions do you need to be aware of for this experiment?

 

EXPERIMENT #1: ANALYSIS OF AN UNKNOWN COMPOUND

Group Experimental Design Pre-lab

 

Include a detailed procedure along with a flowchart drawn in PowerPoint to describe how your separation and tests for unknown ions will be conducted.   This procedure should be written stepwise with the initials of the student who is performing that step in the procedure.  Here is an example:

1. Weigh substance- AW (these are the initials of student performing task)

2. Get the volume of substance – EE

( 1 )

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