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Balancing Chemical Equations
4.3 Reaction Stoichiometry
4.4 Stoichiometric Relationships
100

Balance the following chemical equation:

Cu2O (s) + C (s) → Cu (s) + CO (g)

Cu2O (s) + C (s) --> 2 Cu (s) + CO (g)

100

Balance the following equation and determine how many moles of O2 are required to react completely with 7.2 moles of C6H16

C6H16 (g)+  O2 (g) ⟶  CO2 (g) +  H2 O(g)

72 mol O2

100

What is the limiting reactant?

The reactant that produces the least amount of product, limiting the amount of product in a chemical reaction

200

Balance the following chemical equation:

CO2 (g) + CaSiO3 (s) + H2O (l) → SiO2 (s) + Ca(HCO3)2 (aq)

2 CO2 (g) + CaSiO3 (s) + H2O (l) --> SiO2 (s) + Ca(HCO3)2 (aq)

200

Calculate the number of moles of NO2 that form when 2.5 mol N2O5 reacts completely

2 N2O5 (g) → 4 NO2 (g) + O2 (g)

5 mol NO2

200

What is theoretical yield? How is it different from actual yield?

Theoretical yield is the maximum amount of product that can be made in a chemical reaction based on the amount of limiting reactant. Actual yield is the amount of product actually produced by a chemical reaction, and should always be less than the theoretical yield.

300

Balance the following chemical equation:

Co(NO3)3 (aq) + (NH4)2S (aq) → Co2S3 (s) + NH4NO3 (aq)

2 Co(NO3)3 (aq) + 3 (NH4)2S (aq) --> Co2S3 (s) + 6 NH4NO3 (aq)

300

How many moles of I2 are produced by the reaction of 0.4235 mol of CuCl2 according to the equation below? How many grams?

2 CuCl2+ 4 KI → 2 CuI + 4 KCl+I2

53.74 g I2

300
How do you find percent yield?

(Actual yield ÷ Theoretical yield) x 100%

400

Balance the following: Solid lead (II) sulfide reacts with aqueous hydrobromic acid to form solid lead (II) bromide and dihydrogen monosulfide gas

PbS (s) + 2 HBr (aq) → PbBr2 (s) + H2S (g)

400

How many moles of oxygen are formed when 58.6 g of KNO3 decomposes according to the following reaction?

4 KNO3 (s) → 2 K2O (s) + 2 N2 (g) + 5 O2 (g)

0.724 mol O2

400

What is the theoretical yield (in grams) of sodium chloride for the reaction of 55.0 g Na with 67.2 g Cl2?

111 g Cl2

500

Solid sodium is added to liquid water and reacts to produce hydrogen gas and aqueous sodium hydroxide. Write a balanced chemical equation for this reaction.

2 Na (s) + 2 H2O (l) → H2 + 2 NaOH

500

When 14.01 g sample of N2 reacts with H2 to form ammonia (NH3), what mass (in grams) of ammonia is produced?

N2 + 3 H2 → 2 NH3

17.03 g NH3

500

Chlorobenzene, C6H5Cl, is used in the production of chemicals such as aspirin and dyes. One way that chlorobenzene is prepared is by reacting benzene, C6H6, with chlorine gas according to the following balanced equation.

C6H6 (l) + Cl2 (g) → C6H5Cl (s) + HCl (g)

What is the theoretical yield if 45.6 g of benzene react?

If the actual yield is 63.7 g of chlorobenzene, what is the percent yield?

65.7 g C6H5Cl

97.0% yield