STOICHIOMETRY REVIEW: CHAPTER 6 & CHAPTER 9



STOICHIOMETRY REVIEW: CHAPTER 6 & CHAPTER 9

CHAPTER 6:

Vocabulary:

Mole

Avogadro’s number

Molar Mass

Mass percent

Empirical formula

Molecular formula

• Use chemical formulas to calculate the formula mass, the molar mass, and the percent composition of any given compound.

• Convert between mass, moles, and atoms in a given molar amount of a chemical compound using dimensional analysis.

• Calculate the empirical formula from either a percentage or a mass composition

• Calculate the molecular formula from the empirical formula, and explain the relationship between the two.

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CHAPTER 9:

Vocabulary:

Mole ratio

Stoichiometry

limiting reactant (reagent)

Excess reagent

Theoretical yield

Percent yield

• Define stoichiometry, and use it to determine the mole ratio in stoichiometric calculations; write a mole ratio relating 2 substances in a balanced chemical equation

• Calculate the amount of moles or number of grams of a reactant or product from the amount of a different reactant or product

• Create a stoichiometric relationship for determining which of 2 reactants is a limiting reactant

• Calculate the amount of reactant that is in excess

• Calculate the theoretical yield from the limiting reagent

• Calculate and relate the actual yield and percent yield to the theoretical yield

Practice Problems:

1. In the chemical equation 2A + 2B ( 2C + 2D, if one knows the mass of A and the molar masses of A, B, C, and D, one can determine

a. The mass of any of the reactants or products.

b. The mass of B only

c. The total mass of C and D only.

d. The total mass of A and B only.

2. For the reaction AgNO3 + NaCl ( NaNO3 + AgCl, how many moles of silver chloride, AgCl, are produced from 7 moles of silver nitrate, AgNO3?

e. 1.0 mol c. 7.0 mol

f. 2.3 mole d. 21 mol

3. For the reaction HCl + NaOH ( NaCl + H2O, how many moles of hydrochloric acid are required to produce 150 g of water?

g. 1.50 mol c. 8.32 mol

h. 4.16 mol d. 12.2 mol

4. In the reaction A + B ( C + D, if the quantity of B is insufficient to react with all of A., then…

i. A is the limiting reactant. c. There is no limiting reactant

j. B in the limiting reactant d. Lots of product can be formed.

5. If the percent yield is equal to 100, then

k. The actual yield is greater than the theoretical yield.

l. The actual yield is equal to the theoretical yield

m. The actual yield is less than the theoretical yield.

n. There was no limiting reactant.

6. (TRUE / FALSE) The reagent that runs out first in a chemical reaction is the limiting reagent.

7. Determine the number of moles of atoms of each element in one mole of the following compounds:

a. K2SO4

b. (NH4)2CrO4

8. Calculate the molar mass of each of the compounds listed in the preceding sample problem.

9. What is the mass in grams of 3.04 mol of ammonia vapor, NH3?

10. Calculate the mass of 0.257 mol of calcium nitrate, Ca(NO3)2.

11. How many moles of compound are there in each of the following?

a. 3.82 g SO2

b. 4.15 * 10-3 g C6H12O6

c. 77.1g Cl2

12. How many molecules are there in each of the samples listed in the preceding sample problem?

13. Calculate the percentage composition of sodium nitrate, NaNO3.

14. Calculate the percentage composition of silver sulfate, Ag2SO4.

15. What is the mass percentage of water in the hydrate CuSO2 ( 5H2O)?

16. Zinc chloride, ZnCl2 is 52.02% chlorine by mass.

a. What mass of chlorine is contained in 80.3 g of ZnCl2?

b. How many moles of Cl is this?

17.     Consider the reaction

             I2O5(g) + 5 CO(g) ------->  5 CO2(g) + I2(g)

a)   80.0 grams of iodine(V) oxide, I2O5, reacts with 28.0 grams of carbon monoxide, CO. Determine the mass of iodine I2, which could be produced?

b)   If, in the above situation, only 0.160 moles, of iodine, I2 was produced.

        i) what mass of iodine was produced?

       ii) what percentage yield of iodine was produced.

18. Zinc and sulphur react to form zinc sulphide according to the equation.

                  Zn   +    S   --------->    ZnS

      If  25.0 g of zinc and 30.0 g of sulphur are mixed,

      a)  Which chemical is the limiting reactant?

      b)  How many grams of ZnS will be formed?

      c)  How many grams of the excess reactant will remain after the reaction is over?

19. Which element is in excess when 3.00 grams of Mg is ignited in 2.20 grams of pure oxygen? What mass is in excess? What mass of MgO is formed?

20. How many grams of Al2S3 are formed when 5.00 grams of Al is heated with 10.0 grams S?

21. When MoO3 and Zn are heated together they react

               3 Zn(s) + 2 MoO3(s) ----------> Mo2O3(s) + 3 ZnO(s)

What mass of ZnO is formed when 20.0 grams of MoO3 is reacted with 10.0 grams of Zn?

22. Silver nitrate, AgNO3, reacts with ferric chloride, FeCl3, to give silver chloride, AgCl, and ferric nitrate, Fe(NO3)3.  In a particular experiment, it was plannned to mix a solution containing 25.0 g of AgNO3 with another solution containing 45.0 grams of FeCl3.

a)  Write the chemical equation for the reaction.

b)  Which reactant is the limiting reactant?

c)  What is the maximum number of moles of AgCl that could be obtained from this mixture?

d)  What is the maximum number of grams of AgCl that could be obtained?

e)  How many grams of the reactant in excess will remain after the reaction is over?

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