Question 1

Which of the following best describes why chemical equations must be balanced?

Accepted Answer

To obey the law of conservation of mass, which states that matter cannot be created or destroyed.

Question 2

Given the unbalanced equation for the combustion of propane: $$\mathrm{C_3H_8 + O_2$ \rightarrow CO_2$ + H_2O}$$, what are the correct coefficients to balance the equation?

Accepted Answer

$$1, 5, 3, 4$$

Question 3

A reaction produces 10.0 g of $$\mathrm{N_2O}$$ from heating ammonium nitrate. How many grams of $$\mathrm{NH_4NO_3}$$ were required? (Molar masses: $$\mathrm{N_2O} = 44.02 g/$$mol, $$\mathrm{NH_4NO_3} = 80.05 g/$$mol)

Accepted Answer

$$18.2 g$$

Question 4

Which of the following is a decomposition reaction?

Accepted Answer

$$2\mathrm{$$KClO_3$$}(s) \rightarrow 2\mathrm{KCl}(s) + 3\mathrm{O_2$}(g)$$

Question 5

A sample of glucose ($$\mathrm{C_xH_yO_z}) $$weighing 18.8 g produces 27.6 g $$\mathrm{CO_2$}$$ and 11.3 g $$\mathrm{H_2O}$$ upon combustion. What is the mass of oxygen in the original sample?

Accepted Answer

$$10.0 g$$

Question 6

Which of the following equations is correctly balanced and includes the correct states of matter for the combustion of octane?

Accepted Answer

$$2\mathrm{C_8H_{18}}(l) + 25\mathrm{O_2$}(g) \rightarrow 16\mathrm{CO_2$}(g) + 18\mathrm{H_2O}(g)$$

Question 7

If 5.25 mol of $$\mathrm{NH_3$}$$ react completely with excess $$\mathrm{CO_2$} to $$form urea $$[(\mathrm{NH_2$})_2CO]$$, how many moles of urea are produced? (Equation: $$2\mathrm{NH_3$}(g) + \mathrm{CO_2$}(g) \rightarrow (\mathrm{NH_2$})_2CO(aq) + \mathrm{H_2O}(l))$$

Accepted Answer

$$2.63$$ mol

Question 8

A student mixes 5 moles of CO with 8 moles of $$\mathrm{H_2$} to $$produce methanol ($$\mathrm{CH_3OH}) $$via $$\mathrm{CO}(g) + 2\mathrm{H_2$}(g) \rightarrow \mathrm{CH_3OH}(l). $$What is the limiting reactant?

Accepted Answer

$$\mathrm{H_2$}$$

Question 9

An Alka-Seltzer tablet contains 1.700 g sodium bicarbonate ($$\mathrm{$$NaHCO_3$$}) $$and 1.000 g citric acid ($$\mathrm{H_3C_6H_5O_7}). $$Which is the limiting reactant in the reaction $$3\mathrm{$$NaHCO_3$$}(aq) + \mathrm{H_3C_6H_5O_7}(aq) \rightarrow 3\mathrm{CO_2$}(g) + 3\mathrm{H_2O}(l) + \mathrm{Na_3C_6H_5O_7}(aq)$$?

Accepted Answer

Citric acid ($$\mathrm{H_3C_6H_5O_7})$$

Question 10

In a synthesis of aspirin, 104.8 g of salicylic acid ($$\mathrm{C_7H_6O_3}) $$and 110.9 g of acetic anhydride ($$\mathrm{C_4H_6O_3}) $$are combined. If 105.6 g of aspirin ($$\mathrm{C_9H_8O_4}) $$are produced, what is the percent yield? (Molar masses: $$\mathrm{C_7H_6O_3} = 138.12 g/$$mol, $$\mathrm{C_4H_6O_3} = 102.09 g/$$mol, $$\mathrm{C_9H_8O_4} = 180.15 g/$$mol)

Accepted Answer

$$77.25\%$$

Question 11

Which of the following is the correct empirical formula for a compound containing 0.4224 mol C and 0.423 mol H?

Accepted Answer

$$\mathrm{CH}$$

Question 12

A reaction has a theoretical yield of 136.7 g and an actual yield of 105.6 g. What is the percent yield?

Accepted Answer

$$77.25\%$$

Question 13

Which of the following is a combustion reaction?

Accepted Answer

$$2\mathrm{HCO_2H}(l) + \mathrm{O_2$}(g) \rightarrow 2\mathrm{CO_2$}(g) + 2\mathrm{H_2O}(l)$$

Question 14

If 3.82 mol of CO reacts completely to form $$\mathrm{CO_2$}$$, how many moles of $$\mathrm{O_2$}$$ are required? (Equation: $$2\mathrm{CO}(g) + \mathrm{O_2$}(g) \rightarrow 2\mathrm{CO_2$}(g))$$

Accepted Answer

$$1.91$$ mol

Question 15

Which of the following statements about limiting reactants is correct?

Accepted Answer

The limiting reactant is the one that is completely consumed first, thus determining the maximum amount of product formed.

Question 16

A reaction between 1.700 g $$\mathrm{$$NaHCO_3$$}$$ and 1.000 g $$\mathrm{H_3C_6H_5O_7}$$ produces 0.6874 g $$\mathrm{CO_2$}. $$What is the total mass of products and leftover reactant after the reaction is complete?

Accepted Answer

$$2.700 g$$

Chapter 8: Chemical Reactions – Structured Study Notes

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