Question 1

Which of the following best describes the Law of Conservation of Mass as it applies to chemical reactions?

Accepted Answer

The total mass of reactants must equal the total mass of products.

Question 2

Given the unbalanced equation $$\mathrm{C_2H_4 + O_2$ \rightarrow CO_2$ + H_2O}$$, what is the correct set of coefficients to balance the equation?

Accepted Answer

$$1, 3, 2, 2$$

Question 3

A student burns 1.00 g of butane ($$\mathrm{C_4H_{10}}) in $$excess oxygen. Using the balanced equation $$2\mathrm{C_4H_{10}} + 13\mathrm{O_2$} \rightarrow 8\mathrm{CO_2$} + 10\mathrm{H_2O}$$, what mass of $$\mathrm{CO_2$} is $$produced? (Molar mass of $$\mathrm{C_4H_{10}} = 58.12 g/$$mol, $$\mathrm{CO_2$} = 44.01 g/$$mol)

Accepted Answer

$$3.03 g$$

Question 4

Which of the following statements about limiting reactants is correct?

Accepted Answer

The limiting reactant is completely consumed in the reaction.

Question 5

In the reaction $$4\mathrm{$$FeCO_3$$}(s) + O_2$(g) \rightarrow 2\mathrm{Fe_2O_3}(s) + 4\mathrm{CO_2$}(g)$$, how many oxygen atoms are on the right-hand side of the equation?

Accepted Answer

14

Question 6

A reaction mixture contains 50.0 g of $$\mathrm{N_2O_4} ($$molar mass = 92.02 g/mol) and 45.0 g of $$\mathrm{N_2H_4} ($$molar mass = 32.05 g/mol). For the reaction $$\mathrm{N_2O_4}(l) + 2\mathrm{N_2H_4}(l) \rightarrow 3\mathrm{N_2$}(g) + 4\mathrm{H_2O}(g)$$, what is the limiting reactant?

Accepted Answer

$$\mathrm{N_2O_4}$$

Question 7

If the theoretical yield of a reaction is 34.97 g of Fe and the actual yield is 28.65 g, what is the percent yield?

Accepted Answer

$$81.93\%$$

Question 8

Which of the following is a characteristic of a combustion reaction?

Accepted Answer

It involves a substance reacting with oxygen and releasing heat.

Question 9

How many moles of $$\mathrm{H_2O}$$ are produced from the combustion of 22.0 moles of octane ($$\mathrm{C_8H_{18}}) $$according to the balanced equation $$2\mathrm{C_8H_{18}} + 25\mathrm{O_2$} \rightarrow 16\mathrm{CO_2$} + 18\mathrm{H_2O}$$?

Accepted Answer

198 moles

Question 10

A sample of 58.6 g of $$\mathrm{$$KNO_3$$} ($$molar mass = 101.11 g/mol) decomposes according to $$4\mathrm{$$KNO_3$$}(s) \rightarrow 2\mathrm{K_2O}(s) + 2\mathrm{N_2$}(g) + 5\mathrm{O_2$}(g). $$How many moles of $$\mathrm{O_2$}$$ are formed?

Accepted Answer

0.724 mol

Question 11

Which of the following must always be the same on both sides of a balanced chemical equation?

Accepted Answer

The number of atoms of each kind

Question 12

In a reaction, 15.0 g of calcium gluconate ($$\mathrm{C$$_{12}$$H_{22}$$CaO_{14}}$$, molar mass = 430.372 g/mol) reacts completely. According to 2$$\mathrm{$$C_{12}H$$_{22}$$CaO_{14}}(s) + O_2$(g) \rightarrow 22\mathrm{H_2O}(g) + 21\mathrm{C}(s) + 2\mathrm{CaO}(s) + 3\mathrm{CO_2$}(g)$$, what mass of water is formed? ($$\mathrm{H_2O}$$ molar mass = 18.0 g/mol)

Accepted Answer

$$6.89 g$$

Question 13

Which of the following best describes the reaction of alkali metals with water?

Accepted Answer

They react vigorously, producing hydrogen gas and a hydroxide.

Question 14

A mixture of 1.00 mole of butane ($$\mathrm{C_4H_{10}}) $$and 10.0 moles of $$\mathrm{O_2$} is $$combusted. According to $$2\mathrm{C_4H_{10}} + 13\mathrm{O_2$} \rightarrow 8\mathrm{CO_2$} + 10\mathrm{H_2O}$$, how many moles of $$\mathrm{O_2$}$$ remain after the reaction is complete?

Accepted Answer

3.5 moles

Question 15

Which of the following is a correct statement about theoretical yield?

Accepted Answer

It is the maximum amount of product that can be formed from the limiting reactant.

Question 16

Which of the following reactions is a combustion reaction?

Accepted Answer

$$\mathrm{CH_4$ + 2O_2 \rightarrow CO_2$ + 2H_2O}$$

Question 17

Which of the following best explains why balancing chemical equations is necessary?

Accepted Answer

To satisfy the Law of Conservation of Mass by having equal numbers of each atom on both sides.

Question 18

Which of the following is a product when sodium reacts with water?

Accepted Answer

$$\mathrm{NaOH}$$

Question 19

Which of the following is true about halogen reactions?

Accepted Answer

Halogens react with many metals to form metal halides.

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

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