Gen. Chem. Final Exam

Assuming that a can of soda has the same specific heat as water, calculate the amount of heat (in kilojoules) transferred when one can (about 350 g) is cooled from 25 °C to 3 °C.

-32 kJ

Methane, the main constituent of natural gas, burns in oxygen to yield carbon dioxide and water: CH4(g) + 2 O2(g) → CO2(g) + 2 H2O(l) Use the following information to calculate ΔH° in kilojoules for the combustion of methane: CH4(g) + O2(g) → CH2O(g) + H2O(g) ΔH° = -275.6 kJ CH2O(g) + O2(g) → CO2(g) + H2O(g) ΔH° = -526.7 kJ H2O(l) → H2O(g) ΔH° = -44.0 kJ

-890.3 kJ

How many moles of gas (air) are in the lungs of an average adult with a lung capacity of 3.8 L? Assume that the lungs are at 1.00 atm pressure and a normal body temperature of 37 °C.

0.15 mol

Typical atmospheric pressure on top of Mt. Everest, whose official altitude is 8848 m, is 265 mm Hg. Convert this value to atmospheres.

0.349

In a typical automobile engine, the mixture of gasoline and air in a cylinder is compressed from 1.0 atm to 9.5 atm prior to ignition. If the uncompressed volume of the cylinder is 410 mL, what is the volume in milliliters when the mixture is fully compressed?

43 mL

"Equal volumes of different gases at the same temperature and pressure contain the same molar amounts" is another way of stating A) Avogadro's law. B) Boyle's law. C) Charles' law. D) Graham's law.

A

A catalyst increases the overall rate of reaction by lowering the activation energy, Ea, for A) both the forward reaction and the reverse reaction. B) neither the forward reaction nor the reverse reaction. C) only the forward reaction. D) only the reverse reaction.

A

A catalyst increases the rate of a reaction by providing a different reaction pathway that A) lowers only the activation energy. B) raises only the energy of the products. C) lowers only the energy of the reactants and products. D) All of these are affected by the presence of a catalyst.

A

A mechanism for a naturally occurring reaction that destroys ozone is: Step 1: O3(g) + HO(g) → HO2(g) + O2(g) Step 2: HO2(g) + O(g) → HO(g) + O2(g) Which species is a catalyst? A) HO B) HO2 C) O D) O3

A

As a rule, which of the following phases are not included in the equilibrium constant expression? 1. pure liquids II. pure solids III. aqueous solutions IV. gases A) I, II B) I, IV C) III, IV D) II, III

A

Assign formal charges to each atom in the resonance form for SOCl2 given in the image. A) 0 for Cl, 0 for S, and 0 for O B) 0 for Cl, +1 for S, and -1 for O C) -1 for Cl, +4 for S, and -2 for O D) -1 for Cl, -2 for S, and -2 for O

A

Calculate the hydronium ion concentration in an aqueous solution that contains 2.50 × 10-4 M in hydroxide ion. A) 4.00 × 10-9M B) 4.00 × 10-10M C) 4.00 × 10-11M D) 5.00 × 10-11M

A

Diamond is held together by A) covalent bonds. B) ion-dipole forces. C) van der Waals forces. D) ionic forces.

A

For a liquid solution made by dissolving a solid or a gas in a liquid, the A) liquid is the solute. B) liquid is the solvent. C) solute is the component present in the greatest amount. D) solvent is the component present in the greatest amount.

A

Identify the conjugate acid/base pairs present in an aqueous solution of hydrogen sulfate ion, HSO4-. A) HSO4-/SO42-and H3O+/H2O B) H2SO4/HSO4-and H2O/OH- C) HSO4-/H2O and H3O+/SO42- D) HSO4-/H2O and H2SO4/OH-

A

O2 and O3 are ________ of oxygen. A) allotropes B) isomers C) isotopes D) stereomers

A

Solids having no ordered long-range structure are classified as A) amorphous solids. B) crystalline solids. C) nonmetallic solids. D) covalent network solids.

A

The rubbing alcohol sold in drug stores often is composed of 70% isopropyl alcohol and 30% water. In this solution A) isopropyl alcohol is the solvent. B) water is the solvent. C) both water and isopropyl alcohol are solvents. D) neither water nor isopropyl alcohol is a solvent.

A

Two metals of equal mass with different heat capacities are subjected to the same amount of heat. Which undergoes the smallest change in temperature? A) The metal with the highest heat capacity. B) The metal with the lowest heat capacity. C) Both undergo the same change in temperature. D) You need to know the initial temperatures of both metals.

A

Water has an unusually high A) electrical conductivity. B) heat of combustion. C) heat of formation. D) specific heat.

A

What is the minimum energy barrier that must be overcome for a chemical reaction to occur? A) activation energy B) net energy C) potential energy D) rate limiting energy

A

What is the strongest monoprotic acid of the following set if all the acids are at 0.100 M concentration? A) hydrofluoric acid with Ka= 3.5 × 10-4 B) benzoic acid with Ka= 6.5 × 10-5 C) acetic acid with Ka= 1.8 × 10-5 D) hypochlorous acid with Ka= 3.5 × 10-8

A

When dissolved in water, which of the following compounds is an Arrhenius acid? A) HCN B) NaOH C) NaF D) CH3CH2OH

A

Which of the following liquids will exhibit the highest vapor pressure? A) Br2, bp = 58.8°C B) CH3OH, bp = 64.7°C C) H2O, bp = 100°C D) All exhibit the same vapor pressure.

A

Which of the following statements is not consistent with the properties of a molecular solid? A) a compound that conducts electricity when molten B) a low melting solid C) a solid formed by the combination of two nonmetallic elements D) a solid that is a nonconductor of electricity

A

Which statement below regarding the half-life of a zeroth-order reaction is true? A) Each half-life is half as long as the preceding half-life. B) Each half-life is twice as long as the preceding half-life. C) Each half-life is four times as long as the preceding half-life. D) The half-life remains unchanged throughout the course of the reaction.

A

A 0.50 M solution of a weak acid HA has the same pH as a 0.075 M solution of HCl. Calculate the Ka for HA. A) 0.50 B) 0.075 C) 0.1324 D) 0.01125

B

A three-step mechanism has been suggested for the formation of carbonyl chloride: Step 1: Cl2→ 2 Cl (fast, equilibrium) Step 2: Cl + CO → COCl (fast, equilibrium) Step 3: COCl + Cl2 → COCl2 + Cl (slow) What is the molecularity of the rate-determining step? A) unimolecular B) bimolecular C) termolecular D) none of these

B

A zeroth order reaction is one whose A) rate is zero. B) rate is independent of reactant concentration. C) rate can be found where [A]t= -kt + ln [A]o. D) rate is dependent on none of the reactants.

B

An acidic solution at 25°C has A) [H3O+] > [OH-] > 1 × 10-7 B) [H3O+] > 1 × 10-7M > [OH-]. C) [H3O+] = [OH-] > 1 × 10-7 D) [H3O+] < 1 × 10-7M > [OH-].

B

An approximation of absolute zero was made from an extrapolation of A) P vs. 1/V. B) V vs. T. C) n vs. V. D) V vs. 1/T

B

At 25°C, the pH of a vinegar solution is 2.60. What are the values of [H3O+] and [OH-] in the solution? A) 3.99 × 10-12M, 2.51 × 10-3M B) 2.51 × 10-3M, 3.98 × 10-12M C) 2.51 × 10-3M, 11.40 M D) 2.60 M, 11.40 M

B

At 50°C the value of Kw is 5.5 × 10-14. A basic solution at 50°C has A) [H3O+] < [OH-] < 2 × 10-7 B) [H3O+] < 2 × 10-7M < [OH-]. C) [H3O+] = [OH-] < 2 × 10-7 D) [H3O+] > 2 × 10-7M < [OH-].

B

Biological reactions are catalyzed by A) sugar. B) enzymes. C) fats. D) water.

B

How many lone pairs of electrons are on the I atom in IF ? A) 0 B) 1 C) 2 D) 3

B

Human tears have a concentration of H3O+ that is 3.16 × 10-8. The concentration of OH- in human tears is A) greater than 3.16 × 10-7and tears are acidic. B) greater than 3.16 ×10-7and tears are basic. C) less than 3.16 × 10-7and tears are acidic. D) less than 3.16 × 10-7and tears are basic.

B

If an equal number of moles of the weak acid HCN and the strong base KOH are added to water, is the resulting solution acidic, basic, or neutral? A) acidic B) basic C) neutral

B

Molecules of a liquid can pass into the vapor phase only if the A) liquid has little surface tension. B) molecules have sufficient kinetic energy to overcome the intermolecular forces in the liquid. C) temperature of the liquid is near its boiling point. D) vapor pressure of the liquid is high.

B

Red blood cells are placed into pure water. Which of the following statements is true? A) Water molecules flow out of the red blood cells, causing them to collapse. B) Water flows into the red blood cells, causing them to swell and burst. C) The osmotic pressure of the cell contents increases, causing the cells to burst. D) The osmotic pressure inside the cells equals the osmotic pressure outside.

B

The oxidation of sulfur dioxide by oxygen to sulfur trioxide has been implicated as an important step in the formation of acid rain: 2 SO2(g) + O2(g) ⇌ 2 SO3(g). If the equilibrium partial pressures of SO2, O2, and SO3 are 0.564 atm, 0.102 atm, and 0.333 atm respectively at 1000 K, what is Kp at that temperature? A) 0.292 B) 3.42 C) 5.79 D) 8.11

B

Under thermodynamic standard state conditions the element oxygen occurs as A) O(g) B) O2(g) C) O2(l) D) O3(g)

B

What are the F—Se—F bond angles in SeF6? A) 60° B) 90° C) 109.5° D) 120°

B

What is the hydronium ion concentration of an acid rain sample that has a pH of 3.15? A) 1.41 × 10-11M B) 7.08 × 10-4M C) 3.15 M D) 10.85 M

B

What is the smallest bond angle in SF6? A) 60° B) 90° C) 109.5° D) 120°

B

Which of the following forms a molecular solid? A) lithium chloride B) water C) graphite D) gold

B

Which of the following should have the lowest bond strength? A) HOI B) HOCl C) HOAt D) HOBr

B

Which of the following statements is false regarding the equilibrium constant, Kc? A) Kcfor a reaction at a particular temperature always has the same value. B) Kcfor the reverse reaction is the negative of Kcfor the forward reaction. C) The numerical value of Kcdepends on the form of the balanced equation. D) When quoting Kcit is customary to omit units.

B

Which one of the following is not used to describe the condition of a gas? A) number of moles B) electronic configuration C) temperature D) pressure

B

Which one of the following statements does not describe the equilibrium state? A) Equilibrium is dynamic and there is no net conversion to reactants and products. B) The concentration of the reactants is equal to the concentration of the products. C) The concentration of the reactants and products reach a constant level. D) The rate of the forward reaction is equal to the rate of the reverse reaction.

B

According to kinetic molecular theory, which of the following will decrease the rate of reaction? A) increase the temperature B) increase the concentration C) increase the size of the molecule D) increase the size of the reaction vessel

C

Calculate the hydronium ion concentration in an aqueous solution that contains 2.50 × 10- M in hydroxide ion. A) 4.00 × 10- M B) 4.00 × 10- M C) 4.00 × 10- M D) 5.00 × 10- M

C

Calculate the pH for an aqueous solution of acetic acid that contains 2.15 × 10-3 M hydronium ion. A) 4.65 × 10-12 B) 2.15 × 10-3 C) 2.67 D) 11.33

C

Calculate the pH for an aqueous solution of acetic acid that contains 2.15 × 10-3 M hydronium ion. A) 4.65 × 10-12 B) 2.15 × 10-3 C) 2.67 D) 11.33

C

Consider a bimolecular reaction in the gas phase. Which one of the following changes in condition will not cause an increase in the rate of the reaction? A) add a catalyst B) increase the temperature at constant volume C) increase the volume at constant temperature D) All of these will increase the rate of reaction.

C

If the units for rate are M s-1, what are the units for the rate constant, k, for a zeroth-order reaction? A) s-1 B) M C) M s-1 D) M-1s-1

C

In the lab, you mix two solutions (each originally at the same temperature) and the temperature of the resulting solution decreases. Which of the following is true? A) The chemical reaction is releasing energy. B) The energy released is equal to s × m × ΔT. C) The chemical reaction is absorbing energy. D) The chemical reaction is exothermic.

C

To make a 3.0 M solution, one could take 3.00 moles of solute and add A) 1.00 L of solvent. B) 1.00 kg of solvent. C) enough solvent to make 1.00 L of solution. D) enough solvent to make 1.00 kg of solution.

C

Using the method of initial rates for the reaction A → B, if the initial concentration of A is doubled and the rate of reaction quadruples, what is the order of reaction with respect to A? A) zeroth B) first C) second D) fourth

C

What are the Br∅nsted-Lowry bases in the following chemical reaction? C5H5N(aq) + H2O(l) ⇌ C5H5NH+(aq) + OH-(aq) A) C5H5N, H2O B) C5H5N, C5H5NH+ C) C5H5N, OH- D) C5H5N, H2O, OH-

C

What is the F—B—F bond angle in BF ? A) less than 109.5° B) 109.5° C) 120° D) greater than 120°

C

What is the equilibrium equation for the reaction: NH4NO3(s) ⇌ N2O(g) + 2 H2O(g)? A) Kp= [N2O] B) Kp= [N2O][H2O] C) Kp= [N2O][H2O] D) Kp = [N2O][H2O] / [NH4NO3]

C

What is the strongest acid of the following? A) HOI B) HOBr C) HOCl D) All are equivalent

C

What is the weight percent of vitamin C in a solution made by dissolving 8.00 g of vitamin C, C6H8O6, in 55.0 g of water? A) 87.3% B) 14.5% C) 12.7% D) 85.5%

C

What volume of 3.00 M CH3OH solution is needed to provide 0.500 mol of CH3OH? A) 3.12 mL B) 9.38 mL C) 167 mL D) 150 mL

C

Which of the following Br∅nsted-Lowry acids does not behave as a strong acid when it is dissolved in water? A) HBr B) HCl C) HNO2 D) HClO4

C

Which of the following best explains why ΔHvap is usually higher than ΔHfusion? A) Vaporization occurs at high temperature. B) Vaporization involves the breaking of bonds within molecules. C) Vaporization involves the breaking of all bonds between molecules. D) Vaporization increases the entropy of molecules.

C

Which of the following is expected to have the greatest viscosity? A) C5H12 B) C6H14 C) C5H11OH D) CH4

C

Which of the intermolecular forces is the most important contributor to the high surface tension shown by water? A) dipole-dipole forces B) dispersion forces C) hydrogen bonding D) ion-dipole forces

C

Which type of bonding does sucrose form upon solidification? A) metallic B) amorphous C) molecular D) anionic

C

n an open end manometer, one end of a U-tube filled with mercury is attached to a gas-filled container and the other end is open to the atmosphere. If the gas pressure in the container is less than atmospheric pressure A) Hg will be forced out of the open end of the U-tube. B) the difference between the Hg levels in the two arms will be greater than 76 cm. C) the Hg level will be higher in the arm connected to the container. D) the Hg level will be higher in the arm open to the atmosphere.

C

A mixture of carbon monoxide, hydrogen, and methanol is at equilibrium. The balanced chemical equation is: CO(g) + 2 H2(g) ⇌ CH3OH(g). At 250°C, the mixture contains 0.0960 M CO, 0.191 M H2, and 0.150 M CH3OH. What is the value for Kc? A) 2.33 × 10-2 B) 0.244 C) 4.09 D) 42.8

D

A nitrogen atom in N2 should have a A) charge of 1-. B) partial charge δ-. C) partial charge δ+. D) charge of 0.

D

For the zeroth-order reaction: A → products, what will happen to the rate of reaction if the concentration of A is tripled? A) The rate will be higher. B) The rate will be tripled. C) The rate will be one-third. D) The rate will remain the same.

D

In the electron dot structure of HCN, the # of bonds between C and N are A) 0 B) 1 C) 2 D) 3

D

Kp is related to Kc by the equation Kp = Kc (RT) What is the value of n for the reaction below? NH4NO3(s) ⇌ N2O(g) + 2 H2O(g) A) -2 B) -1 C) +1 D) +2

D

The equilibrium constant, K, for the reaction shown below has a value 1.8 × 10-5. In this reaction which is the strongest acid and which is the strongest base? CH3CO2H(aq) + H2O(l) ⇌ H3O+(aq) + CH3CO2-(aq) A) CH3CO2H and CH3CO2- B) CH3CO2H and H2O C) H3O+and H2O D) H3O+and CH3CO2-

D

The magnitude of the heats of vaporization, fusion and sublimation of a substance reflect the A) density of the substance. B) magnitudes of the boiling and melting points of the substance. C) strength of the covalent bonds between atoms in each molecule of the substance. D) strength of the intermolecular forces of the substance.

D

The vapor pressure of a pure liquid increases as the A) average kinetic energy of the molecules in the liquid phase decreases. B) intermolecular attractive forces increase. C) temperature of the liquid phase decreases. D) temperature of the liquid phase increases.

D

Three identical flasks contain three different gases at standard temperature and pressure. Flask A contains Ar, flask B contains Ne, flask C contains H2. Which flask contains the largest number of molecules? A) flask A B) flask B C) flask C D) All flasks contain the same number of molecules.

D

What factor affects the rate of a chemical reaction? A) collision frequency B) fraction of collisions with sufficient energy C) orientation of molecules D) All of these

D

What is the density of carbon monoxide gas at STP? A) 0.510 g/L B) 0.800 g/L C) 1.96 g/L D) 1.25 g/L

D

What is the strongest acid among the following? A) HF B) HCl C) HBr D) HI

D

When cubic unit cells stack together, how many unit cells share a common corner? A) 2 B) 4 C) 6 D) 8

D

Which general rate law below corresponds to an elementary bimolecular reaction? A) Rate = k[B] B) Rate = k[A][B][C][D] C) Rate = k[A] [B]2 D) Rate = k[A]2

D

Which is the smallest quantity of pressure? A) 1 atm B) 1 centimeter of Hg C) 1 mm Hg D) 1 pascal

D

Which of the following compounds exhibits hydrogen bonding? A) CH3F B) CH3OCH3 C) (CH3)3N D) CH3CH2OH

D

Which of the following does not affect the rate of a bimolecular reaction? A) concentrations of reactants B) presence of a catalyst C) temperature D) All of these affect the rate

D

Which of the following solutions has the highest concentration of hydroxide ions [OH-]? A) pH = 3.21 B) pH = 7.83 C) pH = 10.93 D) pH = 12.04

D

Which of the following statements are true about reaction mechanisms? A rate law can be written from the molecularity of the slowest elementary step. The final rate law can include intermediates. III. The rate of the reaction is dependent on the fastest step in the mechanism. A mechanism can never be proven to be the correct pathway for a reaction. A) I, II, III B) II, IV C) I, III D) I, IV

D

Which will alter the composition of an equilibrium mixture? A) increase the volume B) increase the temperature C) increase the pressure D) all of the above

D

Based on formal charges, the P—O bond order in POCl is expected to be 3 Answer: 2

False

The intermolecular forces responsible for water being at liquid at are hydrogen bonds.

True