Chapter 1

\(\mathrm{CaCO}_{3}(s)+2 \mathrm{H}^{+}(a q) \rightarrow \mathrm{Ca}^{2+}(a q)+\mathrm{H}_{2} \mathrm{O}(l)+\mathrm{CO}_{2}(g)\) If the reaction above took place at standard temperature and pressure and 150 grams of \(\mathrm{CaCO}_{3}(\mathrm{s})\) were consumed, what was the volume of \(\mathrm{CO}_{2}(g)\) produced at STP? (A) 11 L (B) 22 L (C) 34 L (D) 45 L

The above reaction is present at equilibrium in a beaker. A student stirs the mixture. What effect will this have on the reaction rates? (A) It will increase both the forward and reverse reaction rates. (B) It will increase the forward rate, but decrease the reverse rate. (C) It will have no effect on the forward rate, but decrease the reverse rate. (D) It will have no effect on either rate.

\(2 \mathrm{HI}(g)+\mathrm{Cl}_{2}(g) \rightleftharpoons 2 \mathrm{HCl}(g)+\mathrm{I}_{2}(g)+\) energy A gaseous reaction occurs and comes to equilibrium, as shown above. Which of the following changes to the system will serve to increase the number of moles of \(\mathrm{I}_{2}\) present at equilibrium? (A) Increasing the volume at constant temperature (B) Decreasing the volume at constant temperature (C) Increasing the temperature at constant volume (D) Decreasing the temperature at constant volume

Consider the following reaction showing photosynthesis: $$\begin{array}{c}{6 \mathrm{CO}_{2}(g)+6 \mathrm{H}_{2} \mathrm{O}(l) \rightarrow \mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}(s)+6 \mathrm{O}_{2}(g)} \\ {\Delta H=+2800 \mathrm{kJ} / \mathrm{mol}}\end{array}$$ Which of the following is true regarding the thermal energy in this system? (A) It is transferred from the surroundings to the reaction. (B) It is transferred from the reaction to the surroundings. (C) It is transferred from the reactants to the products. (D) It is transferred from the products to the reactants.

A gaseous mixture at \(25^{\circ} \mathrm{C}\) contained 1 mole of \(\mathrm{CH}_{4}\) and 2 moles of \(\mathrm{O}_{2}\) and the pressure was measured at 2 \(\mathrm{atm}\) . The gases then underwent the reaction shown below. \(\mathrm{CH}_{4}(g)+2 \mathrm{O}_{2}(g) \rightarrow \mathrm{CO}_{2}(g)+2 \mathrm{H}_{2} \mathrm{O}(g)\) What was the pressure in the container after the reaction had gone to completion and the temperature was allowed to return to \(25^{\circ} \mathrm{C} ?\) (A) 1 atm (B) 2 \(\mathrm{atm}\) (C) 3 \(\mathrm{atm}\) (D) 4 \(\mathrm{atm}\)

$$2 \mathrm{NOBr}(g) \rightleftharpoons 2 \mathrm{NO}(g)+\mathrm{Br}_{2}(g)$$ The reaction above came to equilibrium at a temperature of \(100^{\circ} \mathrm{C} .\) At equilibrium the partial pressure due to NOBr was 4 atmospheres, the partial pressure due to NO was 4 atmospheres, and the partial pressure due to \(\mathrm{Br}_{2}\) was 2 atmospheres. What is the equilibrium constant, \(K_{p},\) for this reaction at \(100^{\circ} \mathrm{C}\) ? (A) \(\frac{1}{4}\) (B) \(\frac{1}{2}\) (C) 1 (D) 2

During a chemical reaction, NO(g) gets reduced and no nitrogen- containing compound is oxidized. Which of the following is a possible product of this reaction? (A) \(\mathrm{NO}_{2}(g)\) (B) \(\mathrm{N}_{2}(g)\) (C) \(\mathrm{NO}_{3}^{-}(a q)\) (D) \(\mathrm{NO}_{2}^{-}(a q)\)

If the wavelength of the light were to be shortened, how would that effect the kinetic energy of the ejected electron? (A) A shorter wavelength would increase the kinetic energy. (B) A shorter wavelength would decrease the kinetic energy. (C) A shorter wavelength would stop all electron emissions completely. (D) A shorter wavelength would have no effect on the kinetic energy of the ejected electrons.

A sample of water originally at \(25^{\circ} \mathrm{C}\) is heated to \(75^{\circ} \mathrm{C}\) . As the temperature increases, the vapor pressure of the water is also observed to increase. Why? (A) Water molecules are more likely to have enough energy to break free of the intermolecular forces holding them together. (B) The covalent bonds between the hydrogen and oxygen atoms within individual water molecules are more likely to be broken. (C) The strength of the hydrogen bonding between different water molecules will increase until it exceeds the covalent bond energy within individual water molecules. (D) The electron clouds surrounding each water molecule are becoming less polarizable, weakening the intermolecular forces between them.

\(\mathrm{H}_{2}(g)+\mathrm{F}_{2}(g) \rightarrow 2 \mathrm{HF}(g)\) Gaseous hydrogen and fluorine combine in the reaction above to form hydrogen fluride with an enthalpy change of \(-540 \mathrm{kJ}\) . What is the value of the heat of formation of \(\mathrm{HF}(g) ?\) (A) \(-1,080 \mathrm{kJ} / \mathrm{mol}\) (B) \(-270 \mathrm{kJ} / \mathrm{mol}\) (C) 270 \(\mathrm{kJ} / \mathrm{mol}\) (D) 540 \(\mathrm{kJ} / \mathrm{mol}\)