Loose Leaf for General, Organic, and Biochemistry: Exam 4 Review Flashcards

Which of the following statements concerning the reaction below is FALSE?

2HgO(s)---->2Hg(l)+O ₂(g) Enthalpy change=182 kJ

a. There is an increase in entropy in this reaction.

b. This reaction is endothermic.

c. 182 kJ of energy are required for every two moles of HgO that react.

d. The energy of the reactants is greater than the energy of the products.

e.The system absorbs energy from the surroundings in this reaction.

Consider the decomposition of calcium carbonate shown below. Which of the following statements correctly describes this reaction as it occurs in a test tube?

CaCO₃(s) + 42.5 kcal---->CaO(s)+CO₂(g)

a. The test tube would feel warm, since the reaction would absorb heat from the surroundings.

b. The test tube would feel cold, since the reaction would absorb heat from the surroundings.

c. The test tube would feel cold, since the reaction would release heat to the surroundings.

d. The test tube would feel warm, since the reaction would release heat to the surroundings.

e. It is impossible to predict without performing the experiment.

Which statement concerning a reversible reaction at equilibrium is FALSE?

a. The concentration of the products is equal to the concentration of the reactants.

b. The forward and reverse reaction rates are equal.

c. There is no further change in the amount of reactants and products.

d. A stress to the system would cause the system to shift in the direction that best relieves the stress.

e. The equilibrium constant does not change at equilibrium.

The formation of rust (Fe₂O₃) on an exposed piece of metal typically takes several months. Which of the following statements is NOT a reasonable assumption about this chemical reaction?

4Fe(s)+3O₂(g)---->2Fe₂O₃(s)

a. The reaction has a low reaction rate.

b. The reaction has a low activation energy.

c. The rusting of iron would occur faster in the warmer summer months than in the cooler winter months.

d. The rusting of iron would occur slower at higher altitude where the concentration of oxygen is lower.

e. Adding a catalyst would increase the rate of the formation of rust.

For the reaction shown below, K_eq=2x10¹¹. Which of the following statements concerning this system at equilibrium is true?

2CO(g)+O₂(g)<==>2CO₂(g)

a. The equilibrium lies to the left.

b. The equilibrium solution contains equal amounts of CO,O, and CO₂.

c. The reaction is very fast, due to the high value for K_eq.

d. The equilibrium solution contains predominantly CO₂.

e. The equilibrium system contains almost twice as many reactant molecules as product molecules.

What instrument is used for measuring the heat energy absorbed or released in a chemical reaction?

a. Thermometer

b. Calorimeter

c. Thermos

d. Balance

e. Scale

A granola bar contains 185 nutritional Calories. How many kilo-joules is his?

a. 7.74x10^-1 kJ

b. 4.42x10^-2 kJ

c. 442 kJ

d. 733 kJ

e. 1.85x10⁵ kJ

One effect of a catalyst being added to a reaction mixture is____________.

a. to increase the equilibrium constant for the reaction

b. to slow down the rate of the reverse reaction

c. to raise the temperature of the mixture

d. to provide a new pathway for the reaction

e. None of the choices are correct.

Thermodynamics is best described as which of the following?

a. The study of the rates at which reactions take place

b. The field of chemistry that determines the mechanisms of reactions

c. The study of Le Chatelier's Principle

d. The study of heat, energy, and work

e. The study of the mass relationships in chemical reactions

Which of the following represents an exothermic reaction?

a. A(g)+B(g)---->2C(g) enthalpy change = +100kcal

b. A(g)---->B(g)+33 kcal

c. 50 kcal =+2A(g)---->C(g)+D(s)

d. Both A and B are exothermic reactions

e. Bothe A and C are exothermic reactions

For the reaction A(g)---->2B(g),K_eq =4.5x10⁵. Which statement is true for the system at equilibrium?

a. [A]>>[B]

b. There is twice as much B as there is A in the reaction vessel.

c. There is more than 100 times more B than there is A in the reaction vessel.

d. There is twice as much A as there is B in the reaction vessel.

e. Changing the temperature will have no affect on the equilibrium.

Which one of the following, if changed, would change the value of the equilibrium constant, K_eq , of a reaction?

a. concentration of reactants

b. concentration of the products

c. temperature

d. catalyst

e. size of the reaction vessel

The reaction shown below is at equilibrium. Use Le Chatelier's principle to predict the effect of adding ammonia gas to the equilibrium reaction mixture.

N₂(g)+3H₂(g)<==>2NH₃(g)

a. The equilibrium position will remain unchanged.

b. The equilibrium position will shift to the right.

c. The equilibrium position will shift to the left.

d. The equilibrium constant will increase.

e. All of the nitrogen gas will be used up.

Which of the following is a true statement concerning the specific heat of a substance?

a. Specific heat is the amount of heat required to raise one gram of a substance by one degree Celsius.

b. Specific heat is 1.00 cal for all substances.

c. Specific heat is the change in the temperature of a substance as it absorbs heat.

d. Specific heat is the amount of heat required to raise a mole of a substance by ten degrees.

e. Specific heat is the eat given off in a chemical reaction.

Which of the following correctly describes what is meant by the term neutralization?

a. The gain of electrons to form an uncharged species

b. The loss of electrons to form an uncharged species

c. The reaction between an acid and a base to form a salt and water

d. The transfer of electrons from an acid to a base

e. The reaction between an oxidizing agent and a reducing agent

A particular buffer solution consists of a weak acid and its conjugate base. How could this buffer solution be modified so as to increase its buffer capacity against added base?

a. Increase the concentration of the weak acid.

b. Increase the concentration of its conjugate base.

c. Use a strong base and its conjugate acid instead.

d. Use a strong acid and its conjugate base instead.

e. Make the concentrations of the weak acid and its conjugate base equal.

HCl is a strong electrolyte. A bottle of HCl contains the label 0.015 M HCl (aq). Which statement concerning this HCl solution is FALSE?

a. The solution is acidic.

b. The pH of the solution is 1.5.

c. The hydronium ion concentration in this solution is 0.015 M.

d. The solution has a higher concentration of hydronium ions than hydroxide ions.

e. The solution contains dissolved H₃O+ and Cl- ions only; no HCl molecules are present.

What is the conjugate acid of NH₂-?

a. NH^2-

b. NH₃

c. NH₄ ⁺

d. NH₂ ⁺

e. NH₄ ^-

What is the conjugate base of H₂SO₄?

a. SO₄ ^2-

b. HSO₄ ^-

c.H₂SO₃

d. SO₄ ^-

e. H₂PO₄ ⁺

A buffer solution contains carbonic acid (H₂CO₃) and sodium bicarbonate (NaHCO₃), each at a concentration of 0.100 M. The relevant equilibrium is shown below. What is the pH of this buffer solution?

H₂CO₃(aq)+H₂O(l)<==>H₃O⁺(aq)+HCO₃ ^-(aq) K_a=4.5x10 ^-7

a. 4.50

b. 7.00

c. 6.35

d. 7.65

e. 2.16

What is the general term used to describe what is happening in the half reaction shown below?

F₂+2e^----->2F^-

a. oxidation

b. reduction

c. decomposition

d. combustion

e. Both A and B are correct.

An aqueous solution with a low pH is necessary for a certain industrial process. Which of the following solutions would have the lowest pH?

a. 2.0 M NaOH

b. 0.5 M HCl

c. 1.0 M acetic acid

d. 1.0 M HCl

e. All solutions would have the same pH.

Which one of the following is NOT a characteristic property of a base?

a. tastes bitter

b. feels slippery

c. increases [H⁺] in water

d. is corrosive

e. causes many metal ions to precipitate

What generic process occurs at the cathode of a voltaic cell?

a. corrosion

b. combustion

c. electrolysis

d. reduction

e. oxidation

For the reaction shown below, which of the following is a conjugate acid-base pair?

C₅H₅N(aq)+H₂O(l)<===>C₅H₅NH ⁺(aq)+OH^-(aq)

a. C₅H₅N, H₂O

b. C₅H₅N, C₅H₅NH⁺

c. C₅H₅NH⁺, OH^-

d. H₂O, OH^-

e. Both B and D

A patient's urine sample gave a reading of 8.2. What is the value of [H₃O⁺] in this solution?

a. 6.0x10^-9M

b. 1.6x10^-8M

c. 2.7x10^-4M

d. 0.91M

e. 1.6x10⁸M

What is the [OH^-] of a solution which has a pH=10.95?

a. 1.03M

b. 1.1x10^-11M

c. 8.9x10^-4M

d. 3.05M

e. 7.4x10^-5M

Which of the following is NOT an example of an oxidation-reduction reaction?

a. combustion of fossil fuels

b. rusting of iron

c. bleaching a stain

d. a base added to a buffer

e. respiration

What product nucleus results from the alpha decay of radium -226?

a. radium-226m

b. thorium-230

c. radon-222

d. radium-230

e. thorium-222

What is the nuclear symbol for the isotope formed when ¹⁶ ₇N undergoes beta decay?

a. ⁰ _-1e

b. ¹⁶ ₈O

c. ¹⁶ ₆C

d. ²⁰ ₅B

e. ¹⁵ _7N

Which phrase best describes a metastable isotope?

a. an isotope that is only partially stable

b. an isotope that decays by emitting only a gamma ray

c. an isotope that decays only when prompted by neutron bombardment

d. an isotope that is man-made

e. any isotope of an element that is radioactive

What nuclear process is used in commerical nuclear power plants to produce energy?

a. fusion

b. fission

c. metastable induction

d. radiocarbon dating

e. positron emission tomography

Give the missing symbol to the following nuclear reaction.

¹¹ ₆C--->¹¹ ₅B+?

a. ⁴ ₂a

b. ⁰ ₊₁y

c. ⁰ ₊₁e

d. ⁰ _-1e

e. None of the choices are correct.

What is the charge of a beta particle?

a. 0

b. -1

c. 1

d. -2

e. 2

How many electrons are contained in an alpha particle?

a. 0

b. 1

c. 2

d. 4

e. 6

What does the symbol ⁴ ₂He represent?

a. an alpha particle

b. an beta particle

c. a gamma ray

d. a positron

e. a deuteron

Which radioactive emission can be stopped by a few sheets of paper?

a. alpha

b. beta

c. gamma

d. proton

e. electron

Americium-241 is a radioactive isotope used in smoke detectors. If the symbol for this isotope is ²⁴¹ ₉₅Am, which of the following correctly describes it subatomic composition?

a. 241 protons, 241 electrons, 95 neutrons

b. 95 neutrons, 241 electrons, 146 electrons

c. 95 protons, 95 electrons, 51 neutrons

d. 146 neutrons, 95 protons, 51 electrons

e. 95 protons, 95 electrons, 146 neutrons

What type of radioactive decay is illustrated by the following nuclear equation?

¹¹ ₆C---->¹¹ ₅B+⁰ ₊₁e

a. positron emission

b. alpha decay

c. beta decay

d. gamma production

e. helium emission

The half-life of cobalt-60 is 5.3 years. What percent of a sample of cobalt-60 will remain after 21.2 years?

a. 50%

b. 40%

c. 12.5%

d. 10%

e. 6.25%