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PROBLEM SET: 12.3 – Limiting Reagent & Percent Yield

Limiting Reagent Probs:

1) How many grams of NH3 can be produced from the reaction of 28 g of N2 and 25 g of H2?

N2 + 3H2 2NH3

2) How much of the excess reagent in Problem 1 is left over?

3) Silver nitrate and sodium phosphate are reacted in equal amounts of 200.0 g each. How many grams of silver phosphate are produced?

3AgNO3 + Na3PO4 Ag3PO4 + 3NaNO3

4) How much of the excess reagent in Problem 3 is left?

5) The hydrochloric acid, HCl, secreted in your stomach can be neutralized by taking an antacid like aluminum hydroxide, Al(OH)3. If 34.0 g HCl are secreted and 12.0 g Al(OH)3 are taken, is there enough Al(OH)3 to react with all of the HCl? (balance eq. first)

HCl+Al(OH)3AlCl3+H2O

6) What mass of SO2 is produced from the reaction between 31.5 g of S8 and 8.65 g of O2?(balance eq. first)

S8+O2SO2

7) What mass of the excess reagent in Problem 6 is left over?

Percent Yield Probs:

1) Heating an ore of antimony, Sb2S3, in the presence of iron gives the element antimony and iron(II) sulfide. When 15.0 g Sb2S3 reacts with an excess of Fe, 9.84 g Sb is produced.

Sb2S3(s)+ Fe(s) Sb(s) + FeS(s)

A) Balance the equation.

B) What is the theoretical yield of Sb (if 15.0 g Sb2S3 reacts)?

C) What is the percent yield of this reaction?

2) When 84.8 g of iron(III) oxide reacts with an excess of carbon monoxide, 54.3 g of iron is

produced.

Fe2O3(s)+ CO(g) Fe(s) + CO2(g)

A) Balance the equation.

B) What is the theoretical yield of iron?

C) What is the percent yield of this reaction?

3) If 50.0 g of silicon dioxide is heated with an excess of carbon, 27.9 g of silicon carbide is produced.

SiO2(s) + C(s) SiC(s) + CO(g)

A) Balance the equation.

B) What is the theoretical yield of silicon carbide, SiC?

C) What is the percent yield of this reaction?

4) Consider the following reaction:

CaCO3+SO2+O2CaSO4+CO2

A) Balance the equation.

B) When 33.5 g of CaCO3 react with excess SO2 and O2, what is the theoretical yield of CaSO4?

C) In the previous question (4B), if the ACTUAL yield was 37.4 g, what is the PERCENT YIELD?

D) If the above reaction proceeds at 96.8% yield, how many grams of CaSO4 are formed when 5.24 g of SO2 reacts with an excess of CaCO3 and O2?

5) When phosphorus burns in the presence of oxygen, P4O10 is produced. In turn, P4O10 reacts with water to produce phosphoric acid, which is one of the compounds found in acid precipitation.

P4O10 + H2O  H3PO4

A) Balance the equation.

B) When 100.0 g of P4O10react, what is the theoretical yield of phosphoric acid?

C) If the actual yield is 126.2 g of H3PO4, what is the percent yield for this reaction?

6) Coal gasification is a process that converts coal into methane gas. If this reaction has a percent yield of 85.0%, how much methane can be obtained from 1250 g of carbon?

2C + 2H2O  CH4 + CO2 (already balanced!)

7) If the percent yield for the coal gasification process in problem #6 can be increased to 95.0%, how much methane can be obtained from 2750 g of carbon?