Chapter 2

A stock solution of 12.0 M sulfuric acid is made available. What is the best procedure to make up 100.0 mL of 4.0 M sulfuric acid using the stock solution and water prior to mixing? (A) Add 33.3 mL of water to the flask, and then add 66.7 mL of 12.0 M acid. (B) Add 33.3 mL of 12.0 M acid to the flask, and then dilute it with 66.7 mL of water. (C) Add 67.7 mL of 12.0 M acid to the flask, and then dilute it with 33.3 mL of water. (D) Add 67.7 mL of water to the flask, and then add 33.3 mL of 12.0 M acid.

The enthalpy values for several reactions are as follows: (I) \(\mathrm{CH}_{4}(g)+\mathrm{H}_{2}(g) \rightarrow \mathrm{C}(s)+\mathrm{H}_{2} \mathrm{O}(g)\) \(\quad \Delta H=-131 \mathrm{kJ} / \mathrm{mol}_{\mathrm{rxn}}\) (II) \(\mathrm{CH}_{4}(g)+\mathrm{H}_{2} \mathrm{O}(g) \rightarrow 3 \mathrm{H}_{2}(g)+\mathrm{CO}(g)\) \(\quad \Delta H=206 \mathrm{kJ} / \mathrm{mol}_{\mathrm{rxn}}\) (III) \(\mathrm{CO}(g)+\mathrm{H}_{2} \mathrm{O}(g) \rightarrow \mathrm{CO}_{2}(g)+\mathrm{H}_{2}(g)\) \(\quad \Delta H=-41 \mathrm{kJ} / \mathrm{mol}_{\mathrm{rxn}}\) (IV) \(\mathrm{CH}_{4}(g)+2 \mathrm{O}_{2}(g) \rightarrow \mathrm{CO}_{2}(g)+\mathrm{H}_{2} \mathrm{O}(l)\) \(\quad \Delta H=-890 \mathrm{kJ} / \mathrm{mol}_{\mathrm{rxn}}\) In which of the reactions does the amount of energy released by the formation of bonds in the products exceed the amount of energy necessary to break the bonds of the reactants by the greatest amount? (A) Reaction I (B) Reaction II (C) Reaction III (D) Reaction IV

Regarding reaction I, how would the addition of a catalyst affect the enthalpy and entropy changes for this reaction? Enthalpy \(\quad\) Entropy (A) Decrease \(\quad\) Decrease (B) Decrease \(\quad\) No Change (C) No Change \(\quad\) Decrease (D) No Change \(\quad\) No Change

London dispersion forces are caused by (A) temporary dipoles created by the position of electrons around the nuclei in a molecule (B) the three-dimensional intermolecular bonding present in all covalent substances (C) the uneven electron-to-proton ratio found on individual atoms of a molecule (D) the electronegativity differences between the different atoms in a molecule

What is the general relationship between temperature and entropy for diatomic gases? (A) They are completely independent of each other; temperature has no effect on entropy. (B) There is a direct relationship, because at higher temperatures there is an increase in energy dispersal. (C) There is an inverse relationship, because at higher temperatures substances are more likely to be in a gaseous state. (D) It depends on the specific gas and the strength of the intermolecular forces between individual molecules.

Which of the following pairs of ions would make the best buffer with a pH between 6 and 7? \(K_{\mathrm{a}}\) for \(\mathrm{HC}_{3} \mathrm{H}_{2} \mathrm{O}_{2}=1.75 \times 10^{-5}\) \(K_{\mathrm{a}}\) for \(\mathrm{HPO}_{4}^{2-}=4.8 \times 10^{-13}\) (A) \(\mathrm{H}_{2} \mathrm{SO}_{4}\) and \(\mathrm{H}_{2} \mathrm{PO}_{4}\) (B) \(\mathrm{HPO}_{4}^{2-}\) and \(\mathrm{Na}_{3} \mathrm{PO}_{4}\) (C) \(\mathrm{HC}_{3} \mathrm{H}_{2} \mathrm{O}_{2}\) and \(\mathrm{NaC}_{3} \mathrm{H}_{2} \mathrm{O}_{2}\) (D) \(\mathrm{NaOH}\) and \(\mathrm{HC}_{2} \mathrm{H}_{3} \mathrm{O}_{2}\)

A solution contains a mixture of four different compound: \(\mathrm{KCl}(a q),\) \(\mathrm{Fe}\left(\mathrm{NO}_{3}\right)_{3}(a q), \mathrm{MgSO}_{4}(a q),\) and \(\mathrm{N}_{2} \mathrm{H}_{4}(a q) .\) Which of these compounds would be easiest to separate via distillation? (A) \(\mathrm{KCl}(a q)\) (B) \(\mathrm{Fe}\left(\mathrm{NO}_{3}\right)_{3}(a q)\) (C) \(\mathrm{MgSO}_{4}(a q)\) (D) \(\mathrm{N}_{2} \mathrm{H}_{4}(a q)\)

A sample of solid \(\mathrm{MgCl}_{2}\) would be most soluble in which of the following solutions? (A) \(\operatorname{LiOH}(a q)\) (B) \(\operatorname{CBr}_{4}(a q)\) (C) \(\operatorname{Mg}\left(\mathrm{NO}_{3}\right)_{2}(a q)\) (D) \(\mathrm{AlCl}_{3}(a q)\)

Most transition metals share a common oxidation state of \(+2 .\) Which of the following best explains why? (A) Transition metals all have a minimum of two unpaired electrons. (B) Transition metals have unstable configurations and are very reactive. (C) Transition metals tend to gain electrons when reacting with other elements. (D) Transition metals will lose their outermost s-block electrons when forming bonds.

\(2 \mathrm{Ag}^{+}(a q)+\mathrm{Fe}(s) \rightarrow 2 \mathrm{Ag}(s)+\mathrm{Fe}^{2+}(a q)\) Which of the following would cause an increase in potential in the voltaic cell described by the above reaction? (A) Increasing \(\left[\mathrm{Fe}^{2+}\right]\) (B) Adding more \(\mathrm{Fe}(s)\) (C) Decreasing \(\left[\mathrm{Fe}^{2+}\right]\) (D) Removing some \(\mathrm{Fe}(s)\)