Q: Which pair of hydrocarbons has the same mass percentage of carbon?

$$\mathrm{C_2H_4}$$ \text{ and } \mathrm{C_3H_6}$

Q: What are the units of heat capacity?

$$\mathrm{J/K}$$ \text{ or } \mathrm{J/\degree C}$

Q: Which of the following reactions is a formation reaction (i.e., $$\Delta H_{rxn} = \Delta H_f$$ for the product)?

$$2\mathrm{C}(s,\text{graphite}) + 2\mathrm{H_2$}(g) \rightarrow \mathrm{C_2H_4}(g)$$

Q: Which combination of solutions will produce a precipitate?

$$\mathrm{Pb(NO_3$)_2}(aq)$$ \text{ and } $$\mathrm{HCl}(aq)$$

Question 1

When octane ($$\mathrm{C_8H_{18}}) $$combusts completely in oxygen, what are the correct coefficients for the balanced equation: $$\mathrm{C_8H_{18} + O_2$ \rightarrow CO_2$ + H_2O}$$?

Accepted Answer

2, 25, 16, 18

Question 2

Calculate the percentage by mass of ammonia ($$\mathrm{NH_3$}) in $$cisplatin, $$\mathrm{$$PtCl_2$$(NH_3$)_2}. ($$Atomic masses: Pt = 195.08, Cl = 35.45, N = 14.01, H = 1.008)

Accepted Answer

11.35\%

Question 3

How many total atoms are present in $$0.139$$ mol of $$\mathrm{Fe(OH_2$)_6$$^{3+}$$}$$?

Accepted Answer

$$1.59 	imes 10$$^{24}$$

Question 4

A nitrogen oxide is $$63.65\% by $$mass nitrogen. Which of the following could be its molecular formula?

Accepted Answer

$$\mathrm{N_2O}$$

Question 5

Which pair of hydrocarbons has the same mass percentage of carbon?

Accepted Answer

$$\mathrm{C_2H_4}$$ 	ext{ and } \mathrm{C_3H_6}$

Question 6

Propane ($$\mathrm{C_3H_8}) $$combusts in excess oxygen. If $$22.05 g of $$propane produces $$38.0 g of$$ $$\mathrm{CO_2$}$$, what is the percent yield of $$\mathrm{CO_2$}$$? (Molar masses: $$\mathrm{C_3H_8} = 44.10 g/$$mol, $$\mathrm{CO_2$} = 44.01 g/$$mol)

Accepted Answer

57.6\%

Question 7

Which of the following best states the first law of thermodynamics?

Accepted Answer

Energy lost by the system must be gained by the surroundings.

Question 8

Given $$4\mathrm{Al} (s) + 3\mathrm{O}_2 (g) \rightarrow 2\mathrm{Al}_2\mathrm{O}_3 (s)$$, $$\Delta H^\circ = -3351\ \mathrm{kJ}$$, this reaction is:

Accepted Answer

Exothermic, heat is released.

Question 9

What are the units of heat capacity?

Accepted Answer

$$\mathrm{J/K}$$ 	ext{ or } \mathrm{J/\degree C}$

Question 10

Which of the following is a correct statement of Hess's Law?

Accepted Answer

If a reaction is carried out in a series of steps, $$\Delta H$$ for the reaction equals the sum of the enthalpy changes for the individual steps.

Question 11

Which reaction below represents the standard enthalpy of formation ($$\Delta H_f^\circ) $$for $$\mathrm{NO_2$}(g)$$?

Accepted Answer

$$\frac{1}{2}\mathrm{N_2$}(g) + \mathrm{O_2$}(g) \rightarrow \mathrm{NO_2$}(g)$$

Question 12

Which of the following substances has a standard enthalpy of formation ($$\Delta H_f^\circ) $$that is NOT zero?

Accepted Answer

$$\mathrm{F_2$}(s)$$

Question 13

Given the following reactions:

$$\mathrm{A} \rightarrow 2\mathrm{B}$$, $$\Delta H_{rxn} = 456.7\ \mathrm{kJ/mol}$$

$$\mathrm{A} \rightarrow \mathrm{C}$$, $$\Delta H_{rxn} = -22.1\ \mathrm{kJ/mol}$$

What is $$\Delta H$$ for $$2\mathrm{B} \rightarrow \mathrm{C}$$?

Accepted Answer

$$-478.8\ \mathrm{kJ/mol}$$

Question 14

Which of the following reactions is a formation reaction (i.e., $$\Delta H_{rxn} = \Delta H_f$$ for the product)?

Accepted Answer

$$2\mathrm{C}(s,	ext{graphite}) + 2\mathrm{H_2$}(g) ightarrow \mathrm{C_2H_4}(g)$$

Question 15

The energy released by combustion of 1 gram of a substance is called its:

Accepted Answer

Fuel value

Question 16

Which of the following is the balanced molecular equation for the complete neutralization of sulfuric acid by potassium hydroxide in aqueous solution?

Accepted Answer

$$\mathrm{H_2SO_4}(aq) + 2\mathrm{KOH}(aq) \rightarrow 2\mathrm{H_2O}(l) + \mathrm{K_2SO_4}(aq)$$

Question 17

A highly water-soluble compound does not form precipitates with $$\mathrm{Cl^-}$$, $$\mathrm{Br^-}$$, $$\mathrm{I^-}$$, $$\mathrm{SO_4$^{2-}}$$, $$\mathrm{CO_3$^{2-}}$$, $$\mathrm{PO_4$^{3-}}$$, $$\mathrm{OH^-}$$, or $$\mathrm{S$$^{2-}$$}. $$When acidified, it produces a foul-smelling gas, $$\mathrm{H_2S}. $$What is the compound?

Accepted Answer

$$(\mathrm{NH_4$})_2\mathrm{S}$$

Question 18

What is the net ionic equation for the reaction of solid nickel(II) carbonate with aqueous hydriodic acid, producing aqueous nickel(II) iodide and carbon dioxide gas?

Accepted Answer

$$\mathrm{$$NiCO_3$$}(s) + 2\mathrm{H^+}(aq) \rightarrow \mathrm{H_2O}(l) + \mathrm{CO_2$}(g) + \mathrm{Ni$$^{2+}$$}(aq)$$

Question 19

Which combination of solutions will produce a precipitate?

Accepted Answer

$$\mathrm{Pb(NO_3$)_2}(aq)$$ 	ext{ and } $$\mathrm{HCl}(aq)$$

Question 20

With which of the following ions will the ammonium ion ($$\mathrm{NH_4$^+}) $$form an insoluble salt?

Accepted Answer

None of the above

Question 21

What is the net ionic equation for the reaction between aqueous sulfuric acid and aqueous sodium hydroxide?

Accepted Answer

$$\mathrm{H^+}(aq) + \mathrm{OH^-}(aq) \rightarrow \mathrm{H_2O}(l)$$

Step-by-Step Guidance for General Chemistry Exam 2 Practice (Chapters 3–5)

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