Q: Which of the following is a correct balanced equation for the combustion of butane ($$\text{C}_4\text{H}_{10}$$)?

$$2\text{C}_4\text{H}_{10} + 13 \text{O}_2 \rightarrow 8 \text{CO}_2 + 10 \text{H}_2\text{O}$$

Q: Which of the following statements about percent yield is correct?

Percent yield is calculated as $$\frac{\text{actual yield}}{\text{theoretical yield}} \times 100\%.$$

Q: Which of the following is the correct empirical formula for a compound containing 68.2% C, 6.86% H, 15.9% N, and 9.08% O by mass?

$$\text{C}_{10}\text{H}_{12}\text{N}_2\text{O}$$

Q: Which of the following reactions is an example of a halogen forming a hydrogen halide?

$$\text{Cl}_2 + \text{H}_2 \rightarrow 2\text{HCl}$$

Question 1

Which of the following best describes the role of a limiting reactant in a chemical reaction?

Accepted Answer

It is the reactant that is completely consumed first, thus limiting the amount of product that can be formed.

Question 2

Given the balanced equation $$2 	ext{H}_2 + 	ext{O}_2 ightarrow 2 	ext{H}_2	ext{O}$$, how many grams of $$	ext{O}_2$$ are required to produce 57 g of $$	ext{H}_2	ext{O}$$? (Molar mass: $$	ext{H}_2	ext{O} = 18.0 g/$$mol, $$	ext{O}_2 = 32.0 g/$$mol)

Accepted Answer

$$50.7 g$

Question 3

A student burns 2.50 moles of propane ($$	ext{C}_3	ext{H}_8) in $$excess oxygen. According to the balanced equation $$	ext{C}_3	ext{H}_8 + 5 	ext{O}_2 ightarrow 3 	ext{CO}_2 + 4 	ext{H}_2	ext{O}$$, how many moles of water are produced?

Accepted Answer

$$10.0$$ moles

Question 4

In a reaction, 10.0 g of aluminum reacts with 15.0 g of sulfur to form aluminum sulfide ($$2	ext{Al} + 3	ext{S} ightarrow 	ext{Al}_2	ext{S}_3). $$What is the limiting reactant?

Accepted Answer

Sulfur

Question 5

Which of the following is a correct balanced equation for the combustion of butane ($$	ext{C}_4	ext{H}_{10}$$)?

Accepted Answer

$$2	ext{C}_4	ext{H}_{10} + 13 	ext{O}_2 ightarrow 8 	ext{CO}_2 + 10 	ext{H}_2	ext{O}$$

Question 6

A reaction yields 1.31 g of methyl salicylate ($$	ext{C}_8	ext{H}_8	ext{O}_3) $$from 1.50 g of salicylic acid and 11.20 g of methanol. If the theoretical yield is 1.84 g, what is the percent yield?

Accepted Answer

$$71.2\%$$

Question 7

Which of the following best explains why the reaction of potassium with water is more vigorous than that of lithium with water?

Accepted Answer

Potassium atoms lose electrons more easily due to their larger atomic radius.

Question 8

If 209 g of methanol ($$	ext{CH}_3	ext{OH}$$, molar mass = 32.0 g/mol) are combusted according to $$2	ext{CH}_3	ext{OH} + 3	ext{O}_2 ightarrow 2	ext{CO}_2 + 4	ext{H}_2	ext{O}$$, what mass of water is produced?

Accepted Answer

$$261 g$$

Question 9

Which of the following statements about percent yield is correct?

Accepted Answer

Percent yield is calculated as $$\frac{	ext{actual yield}}{	ext{theoretical yield}} 	imes 100\%.$$

Question 10

Which of the following is a correct interpretation of the coefficients in the balanced equation $$	ext{C}_3	ext{H}_8 + 5 	ext{O}_2 ightarrow 3 	ext{CO}_2 + 4 	ext{H}_2	ext{O}$$?

Accepted Answer

1 molecule of propane reacts with 5 molecules of oxygen to produce 3 molecules of carbon dioxide and 4 molecules of water.

Question 11

A reaction between 1.54 x $$10^3 g of$$ $$	ext{V}_2	ext{O}_5$$ and 1.96 x $$10^3 g of Ca $$produces vanadium according to $$5	ext{Ca} + 	ext{V}_2	ext{O}_5 ightarrow 5	ext{CaO} + 2	ext{V}. If 803 g of V $$are obtained, what is the percent yield?

Accepted Answer

$$41.0\%$$

Question 12

Which of the following best describes a combustion reaction?

Accepted Answer

A reaction in which a substance reacts with oxygen to form one or more oxygen-containing compounds and emits heat.

Question 13

When sodium reacts with chlorine gas, what type of compound is formed?

Accepted Answer

A metal halide

Question 14

Which of the following is the correct empirical formula for a compound containing 68.2% C, 6.86% H, 15.9% N, and 9.08% O by mass?

Accepted Answer

$$	ext{C}_{10}	ext{H}_{12}	ext{N}_2	ext{O}$$

Question 15

Which of the following reactions is an example of a halogen forming a hydrogen halide?

Accepted Answer

$$	ext{Cl}_2 + 	ext{H}_2 ightarrow 2	ext{HCl}$$

Question 16

If 12.0 g of Al reacts with excess $$	ext{Fe}_2	ext{O}_3$$ according to $$	ext{Fe}_2	ext{O}_3 + 2	ext{Al} ightarrow 	ext{Al}_2	ext{O}_3 + 2	ext{Fe}$$, how many moles of $$	ext{Al}_2	ext{O}_3$$ are produced? (Molar mass Al = 27.0 g/mol)

Accepted Answer

$$0.222$$ mol

Question 17

Which of the following best describes the product(s) when an alkali metal reacts with water?

Accepted Answer

A metal hydroxide and hydrogen gas

Question 18

A solution of calcium chloride is mixed with sodium phosphate. What is the solid product formed?

Accepted Answer

Calcium phosphate

Question 19

Which of the following is a correct step in balancing a chemical equation?

Accepted Answer

Change only the coefficients in front of the compounds.

Chemical Reactions and Chemical Quantities: Stoichiometry, Limiting Reactants, and Types of Reactions

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