Chapter 1

In which of the following compounds is the oxidation number of chromium the greatest? (A) \(\mathrm{CrO}_{4} 2^{-}\) (B) \(\mathrm{CrO}\) (C) \(\mathrm{Cr}^{3+}\) (D) \(\operatorname{Cr}(s)\)

$$2 \mathrm{NOCl} \rightarrow 2 \mathrm{NO}+\mathrm{Cl}_{2}$$ The reaction above takes place with all of the reactants and products in the gaseous phase. Which of the following is true of the relative rates of disappearance of the reactants and appearance of the products? (A) NO appears at twice the rate that NOCl disappears. (B) NO appears at the same rate that NOCl disappears. (C) NO appears at half the rate that NOCl disappears. (D) \(\mathrm{Cl}_{2}\) appears at the same rate that NOCl disappears.

The following reaction is found to be at equilibrium at 25°C: \(2 \mathrm{SO}_{3}(g) \leftrightarrow \mathrm{O}_{2}(g)+2 \mathrm{SO}_{2}(g) \quad \Delta H=-198 \mathrm{kJ} / \mathrm{mol}\) The value for \(K_{\mathrm{c}}\) at \(25^{\circ} \mathrm{C}\) is \(8.1 .\) What must happen in order for the reaction to reach equilibrium if the initial concentrations of all three species was 2.0 \(M\) ? (A) The rate of the forward reactions would increase, and \(\left[\mathrm{SO}_{3}\right]\) would decrease. (B) The rate of the reverse reaction would increase, and \(\left[\mathrm{SO}_{2}\right]\) would decrease. (C) Both the rate of the forward and reverse reactions would increase, and the value for the equilibrium constant would also increase. (D) No change would occur in either the rate of reaction or the concentrations of any of the species.

The first ionization energy for a neutral atom of chlorine is 1.25 \(\mathrm{MJ} / \mathrm{mol}\) and the first ionization energy for a neutral atom of argon is 1.52 \(\mathrm{MJ} / \mathrm{mol}\) How would the first ionization energy value for a neutral atom of potassium compare to those values? (A) It would be greater than both because potassium carries a greater nuclear charge then either chlorine or argon. (B) It would be greater than both because the size of a potassium atom is smaller than an atom of either chlorine or argon. (C) It would be less than both because there are more electrons in potassium, meaning they repel each other more effectively and less energy is needed to remove one. (D) It would be less than both because a valence electron of potassium is farther from the nucleus than one of either chlorine or argon.

For an endothermic reaction, which of the following is true regarding the energy level of the activated complex? (A) It is above the energy level of the reactants, but below the energy level of the products. (B) It is below the energy level of the reactants, but above energy level of the products. (C) It is above the energy level of both the products and reactants. (D) It is below the energy level of both the products and reactants.

Which of the following compounds would have the highest lattice energy? (A) LiF (B) MgCl_ (C) CaBr_ (D) \(\mathrm{C}_{2} \mathrm{H}_{6}\)

\(\begin{array}{ll}{\mathrm{C}(s)+2 \mathrm{H}_{2}(g) \rightarrow \mathrm{CH}_{4}(g)} & {\Delta H^{\circ}=x} \\\ {\mathrm{C}(s)+\mathrm{O}_{2}(g) \rightarrow \mathrm{CO}_{2}(g)} & {\Delta H^{\circ}=y} \\ {\mathrm{H}_{2}(g)+\frac{1}{2} \mathrm{O}_{2}(g) \rightarrow \mathrm{H}_{2} \mathrm{O}(l)} & {\Delta H^{\circ}=\mathrm{z}}\end{array}\) Based on the information given above, what is \(\Delta H^{\circ}\) for the following reaction? \(\mathrm{CH}_{4}(g)+2 \mathrm{O}_{2}(g) \rightarrow \mathrm{CO}_{2}(g)+2 \mathrm{H}_{2} \mathrm{O}(l)\) (A) \(x+y+z\) (B) \(x+y-z\) (C) \(z+y-2 x\) (D) \(2 z+y-x\)

The following reaction is found to be at equilibrium at 25°C: \(2 \mathrm{SO}_{3}(g) \leftrightarrow \mathrm{O}_{2}(g)+2 \mathrm{SO}_{2}(g) \quad \Delta H=-198 \mathrm{kJ} / \mathrm{mol}\) Which of the following would cause a reduction in the value for the equilibrium constant? (A) Increasing the amount of \(\mathrm{SO}_{3}\) (B) Reducing the amount of \(\mathrm{O}_{2}\) (C) Raising the temperature (D) Lowering the temperature

$$\mathrm{H}_{2}(g)+\mathrm{I}_{2}(g) \rightarrow 2 \mathrm{HI}(g)$$ When the reaction given above takes place in a sealed isothermal container, the rate law is $$\text { Rate }=k\left[\mathrm{H}_{2}\right]\left[\mathrm{I}_{2}\right]$$ If a mole of \(\mathrm{H}_{2}\) gas is added to the reaction chamber and the temperature remains constant, which of the following will be true? (A) The rate of reaction and the rate constant will increase. (B) The rate of reaction and the rate constant will not change. (C) The rate of reaction will increase and the rate constant will decrease. (D) The rate of reaction will increase and the rate constant will not change.

Which of the following isoelectric species has the smallest radius? (A) \(\mathrm{S}^{2-}\) (B) \(\mathrm{Cl}^{-}\) (C) Ar (D) \(\mathrm{K}^{+}\)