TABLE OF CONTENTS

(del) Open Source CA Textbook - Chemistry

OLD Unit 4: Gases and Their Properties

Unit 3: Conservation of Matter & Stoichiometry

CHEMISTRY EXAM #6:

15% OLD STUFF


  1. Explain how you balance equations? (2pt)



2. Please write the formula for each of the following: (2pts each)

Calcium Nitrate:
Heptane:

3. Please calculate the total number of atoms in: 3Pb2(SO4)4: (4pts) _________________



4. Please balance the following equation (5pts)

C6H12 + O2 ? CO2 + H2O



NEW STUFF


Multiple Choice: Please select the single best answer in each of the following (3pts each)

5. Which of the following is not a mole of the substance?:
a) 32.000g oxygen gas
b) 12.011 g carbon gas
c) 28.014 g nitrogen gas
d) 4.003 g helium gas
e) All of the above are moles of the substance

6. Fewer steps are required to solve stoichiometry problems when the reactant is given in :
a) grams and the product is sought in grams
b) atoms and the product is sought in moles
c) grams and the product is sought in fu
d) atoms and the product is sought in grams
e) All of the above require the same number of steps

7. When doing chemical reactions in industry, the ............ chemical is often chosen as the excess reagent.
a) Least expensive and most common
b) Most expensive and least common
c) Least expensive and least common
d) Most expensive and most common
e) All are equally likely to be used

8. In the reaction P4 + 5O2 ? P4O10, if 2 moles of phosphorus react with 10 moles of oxygen, the theoretical yield of the product will be:
a) 1 mol
b) 2 mol
c) 3 mol
d) 10 mol
e) None of the above


Please convert to scientific notation (2pts each):

9. 343, 930 Please convert to standard notation (2pts):

10. 8.45 x 10-5 ______________________________________________________

    1. How many seconds are in a decade? (5pts)

PROBLEMS

12. If you have 500g of Potassium Nitrate, how many formula units of it do you have? (8pts)







13. If you begin with 150g of Barium Sulfide and react it with excess Sodium Chloride, how much Barium Chloride will you produce? (10pts)












14. Given the balanced equation: NaHCO3 + HCl ? NaCl + H2O + CO2, Assume that you start with 10.0g of sodium bicarbonate and you end up with 20.0g of salt, what was your percent yield for this reaction? (10pts)

15. In the balanced reaction: 2Na + 2H2O ? 2NaOH + H2, prove which is the limiting reactant if 100.0 g of Na and 50.0 g of H2O are available? (10pts)















16. Please list the steps that you would need to do in order to calculate a % yield? (6pts)







ESSAY QUESTIONS

Please answer 2 of the following 3 questions.

17. Explain the importance of coefficients in balanced equations. Please explain what they represent and how they are useful in chemistry. (10pts)
18. You begin with 45.76 g of salt and an unlimited supply of Lead (III) Oxide. How many grams of Lead (III) Chloride are produced? Oh yeah, Lead (III) Oxide and salt don’t react with one another. Explain in words, how you would solve this problem. (10pts)
19. Lurpy is about to receive his PhD in Chemistry from Nutria University (NU). He has but one problem left to work before he gets his degree, but he needs your help. The problem is as such: Lurpy’s new girlfriend Nina synthesized some salt in the lab. She started with 50 grams of chlorine and ended up with 100 grams of salt. Explain why this is a problem and offer reasons (at least 3) for why this may have happened. Don’t let Lurpy down! (10pts)

INSURANCE POINTS

To be added onto your exam total…they can’t hurt you! (2pts each)

What is the definition of penultimate? __________________________________________

What do you have to do to form a salt? __________________

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