Question 1

Which of the following best describes the process of balancing a chemical equation for the combustion of propane ($$\mathrm{C_3H_8}$$)?

Accepted Answer

Balance carbon atoms first, then hydrogen, then oxygen.

Question 2

Given the reaction $$\mathrm{C_3H_8(g) + 5O_2(g) \rightarrow 3CO_2(g) + 4H_2O(g)}$$, how many moles of $$\mathrm{O_2$}$$ are required to completely combust 2 moles of propane ($$\mathrm{C_3H_8}$$)?

Accepted Answer

$$10$$ moles

Question 3

Which compound will precipitate when aqueous solutions of silver nitrate ($$\mathrm{$$AgNO_3$$}) $$and sodium chloride ($$\mathrm{NaCl}) $$are mixed?

Accepted Answer

$$\mathrm{AgCl}$$

Question 4

What is the net ionic equation for the reaction between aqueous solutions of zinc acetate and potassium hydroxide?

Accepted Answer

$$\mathrm{Zn$$^{2+}$$(aq) + 2OH^-(aq) \rightarrow Zn(OH)_2(s)}$$

Question 5

Which of the following compounds is insoluble in water according to the solubility rules?

Accepted Answer

Silver chloride ($$\mathrm{AgCl})$$

Question 6

Which of the following statements about oxidation and reduction is correct?

Accepted Answer

Oxidation is the loss of electrons; reduction is the gain of electrons.

Question 7

In the reaction $$\mathrm{Zn(s) + Cu$$^{2+}$$(aq) \rightarrow Zn$$^{2+}$$(aq) + Cu(s)}$$, which species is the reducing agent?

Accepted Answer

$$\mathrm{Zn}$$

Question 8

Calculate the formula weight of potassium carbonate ($$\mathrm{K_2CO_3}) $$using the following atomic weights: K = 39.1, C = 12.0, O = 16.0.

Accepted Answer

$$138.2$$

Question 9

How many molecules of aspirin ($$\mathrm{C_9H_8O_4}$$, molar mass = 180.0 g/mol) are present in a 0.360 g tablet?

Accepted Answer

$$1.20 	imes 10$$^{21}$$

Question 10

A reaction produces 57.8 g of acetic acid when the theoretical yield is 60.0 g. What is the percent yield?

Accepted Answer

$$96.3\%$$

Question 11

If 5.63 g of sodium sulfate ($$\mathrm{Na_2SO_4}$$, molar mass = 142.1 g/mol) is dissolved in water, how many moles of sodium ions ($$\mathrm{Na^+}) $$are present?

Accepted Answer

$$0.0792$$ mol

Question 12

Which of the following is true about limiting reagents in a chemical reaction?

Accepted Answer

The limiting reagent is the one that is used up first.

Question 13

How many grams of $$\mathrm{CO_2$}$$ are produced when 12 g of carbon reacts with excess oxygen? ($$\mathrm{C + O_2$ \rightarrow CO_2$}$$, molar mass $$\mathrm{CO_2$} = 44 g/$$mol)

Accepted Answer

$$44 g$$

Question 14

Which of the following reactions is an example of an exothermic reaction?

Accepted Answer

Combustion of methane

Question 15

How much heat is required to raise the temperature of 352 g of water from 23°C to 95°C? (Specific heat of water = $$1.00 \ \mathrm{cal/g \cdot ^\circ C})$$

Accepted Answer

$$2.5 	imes 10^4$ cal

Question 16

Which of the following best describes a spectator ion?

Accepted Answer

An ion that is present in solution but does not participate in the reaction.

Question 17

Which of the following is the correct formula for calculating percent yield?

Accepted Answer

$$\mathrm{Percent\ yield = \frac{Actual\ yield}{Theoretical\ yield} 	imes 100}$$

Question 18

A sample of iron (Fe) is heated from 23°C to 176°C, requiring 88.2 cal for 13.4 g of Fe. What is the specific heat of iron?

Accepted Answer

$$0.11 \ \mathrm{cal/g \cdot ^\circ C}$$

Question 19

Which of the following is NOT a type of redox reaction discussed in the materials?

Accepted Answer

Precipitation

Chemical Reactions: Equations, Stoichiometry, and Energy Changes

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