Theoretical Yield and Limiting Reactant Test Questions

Chemistry Test Questions

The theoretical yield of products in a chemical reaction can be predicted from the stoichiometric ratios of the reactants and products of the reaction. These ratios can also be used to determine which reactant will be the first reactant to be consumed by the reaction. This reactant is known as the limiting reagent. This collection of ten chemistry test questions deals with the subjects of theoretical yield and limiting reagent.

The answers appear after the final question. A periodic table may be required to complete the questions.

Question 1

Surface level view of sea
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The minerals in seawater can be obtained through evaporation. For every liter of seawater evaporated, 3.7 grams of Mg(OH)2 can be obtained.

How many liters of seawater must be evaporated to collect 5.00 moles of Mg(OH)2?

Question 2

Water can be separated into hydrogen and oxygen gases by using electricity to break the bonds in a process called electrolysis. The reaction is:

H2O → 2 H2(g) + O2(g)

How many moles of H2 gas would be formed from the electrolysis of 10 moles of water?

Question 3

Copper sulfate and zinc metal react to form zinc sulfate and copper by the reaction:

CuSO4 + Zn → ZnSO4 + Cu

How many grams of copper are produced from 2.9 grams of zinc consumed with excess CuSO4 in this reaction?

Question 4

Sucrose (C12H22O11) combusts in the presence of oxygen to produce carbon dioxide and water by the reaction:

C12H22O11 + 12 O2 → CO2 + 11 H2O.

How many grams of CO2 are produced if 1368 grams of sucrose is combusted in presence of excess O2?

Question 5

Consider the following reaction:

Na2S(aq) + AgNO3(aq) → Ag2S(s) + NaNO3(aq)

How many grams of Ag2S can be produced from 7.88 grams of AgNO3 and excess Na2S?

Question 6

129.62 grams of silver nitrate (AgNO3) are reacted with 185.34 grams of potassium bromide (KBr) to form solid silver bromide (AgBr) by the reaction:

AgNO3(aq) + KBr(aq) → AgBr(s) + KNO3

a. Which reactant is the limiting reagent?
b. How much silver bromide is formed?

Question 7

Ammonia (NH3) and oxygen combine to form nitrogen monoxide (NO) and water by the chemical reaction:

4 NH3(g) + 5 O2(g) → 4 NO(g) + 6 H2O(l)

If 100 grams of ammonia are reacted with 100 grams of oxygen

a. Which reagent is the limiting reagent?
b. How many grams of the excess reagent remains at completion?

Question 8

Sodium metal strongly reacts with water to form sodium hydroxide and hydrogen gas by the reaction:

2 Na(s) + 2 H2O(l) → 2 NaOH(aq) + H2(g)

If a 50-gram

a. Which is the limiting reagent? b. How many moles of hydrogen gas are produced?

Question 9

Iron(III) oxide (Fe2O3) combines with carbon monoxide to form iron metal and carbon dioxide by the reaction:

Fe2O3(s) + 3 CO(g) → 2 Fe(s) + 3 CO2

If 200 grams of iron(III) oxide are reacted with 268 grams of carbon dioxide,

a. Which reactant is the limiting reactant? b. How many grams of iron should be produced at completion?

Question 10

The poison phosgene (COCl2) can be neutralized with sodium hydroxide (NaOH) to produce salt (NaCl), water, and carbon dioxide by the reaction:

COCl2 + 2 NaOH → 2 NaCl + H2O + CO2

If 9.5 grams of phosgene and 9.5 grams of sodium hydroxide are reacted:

a. will all of the phosgene be neutralized?
b. If so, how much sodium hydroxide remains? If not, how much phosgene remains?

Answers

1. 78.4 liters of seawater
2. 20 moles of H2 gas
3. 2.8 grams of copper
4. 2112 grams of CO2
5. 5.74 grams of Ag2S
6. a. silver nitrate is the limiting reagent. b. 143.28 g of silver bromide is formed
7. a. Oxygen is the limiting reagent. b. 57.5 grams of ammonia remain.
8. a. Sodium is the limiting reagent. b. 1.1 moles of H2.
9. a. Iron(III) oxide is the limiting reagent. b. 140 grams of iron
10. a. Yes, all of the phosgene will be neutralized. b. 2 grams of sodium hydroxide remains.

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Helmenstine, Todd. "Theoretical Yield and Limiting Reactant Test Questions." ThoughtCo, Jun. 29, 2017, thoughtco.com/theoretical-yield-and-limiting-reactant-test-questions-604130. Helmenstine, Todd. (2017, June 29). Theoretical Yield and Limiting Reactant Test Questions. Retrieved from https://www.thoughtco.com/theoretical-yield-and-limiting-reactant-test-questions-604130 Helmenstine, Todd. "Theoretical Yield and Limiting Reactant Test Questions." ThoughtCo. https://www.thoughtco.com/theoretical-yield-and-limiting-reactant-test-questions-604130 (accessed January 23, 2018).