First Semester Study Guide - AP Chem - Buck

A reaction in which the same reactant undergoes both oxidation and reduction

A

In which of the following systems would the number of moles of the substances present at equilibrium NOT be shifted by a change in the volume of the system at constant temperature?

A

The diagram above represents H2(g) and N2(g) in a closed container. Which of the following diagrams would represent the results if the reaction shown below were to proceed as far as possible?

A

How many moles of solid Ba(NO3)2 should be added to 300. milliliters of 0.20-molar Fe(NO3)3 to increase the concentration of the NO3 ̄ ion to 1.0-molar? (Assume that the volume of the solution remains constant.) a. 0.060 mole b. 0.40 mole c. 0.24 mole d. 0.30 mole e. 0.12 mole

A. 0.060 mole

Which of the following solutions has a pH greater than 7.0? a. 0.10 M NaF b. 0.10 M HC2H3O2 c. 0.10 M NH4Cl d. 0.10 M HI e. 0.10 M KBr

A. 0.10 M NaF

In a titration experiment based on the equation above, 25.0 milliliters of an acidified Fe2+ solution requires 14.0 milliliters of standard 0.050-molar MnO4 ̄ solution to reach the equivalence point. The concentration of Fe2+ in the original solution is a. 0.14 M b. 0.0056 M c. 0.090 M d. 0.028 M e. 0.0010 M

A. 0.14 M

A 20.0-milliliter sample of 0.200-molar K2CO3 solution is added to 30.0 milliliters of 0.400-molar Ba(NO3)2 solution. Barium carbonate precipitates. The concentration of barium ion, Ba2+, in solution after reaction is a. 0.160 M b. 0.240 M c. 0.267 M d. 0.150 M e. 0.200 M

A. 0.160 M

rate = k[X] For the reaction whose rate law is given above, a plot of which of the following is a straight line? a. 1/[X] versus time b. log [X] versus time c. [X] versus time d. log [X] versus 1/time e. [X] versus 1/time

A. 1/[X] versus time

When 0.40 mole of SO2 and 0.60 mole of O2 are placed in an evacuated 1.00-liter flask, the reaction represented above occurs. After the reactants and the product reach equilibrium and the initial temperature is restored, the flask is found to contain 0.30 mole of SO3. Based on these results, the equilibrium constant, Kc, for the reaction is a. 20. b. 2.0 c. 10. d. 6.7 e. 1.2

A. 20

Which of the following pieces of laboratory glassware should be used to most accurately measure out a 25.00 mL sample of a solution a. 25 mL pipet b. 25 mL Erlenmeyer flask c. 25 mL beaker d. 5 mL pipet e. 50 mL graduated cylinder

A. 25 mL pipet

The density of a pure liquid at 25°C was calculated by determining the mass and volume of a sample of the liquid. A student measures the mass of a clean, dry 25.00 mL volumetric flask, filled the flask to its calibration mark with the liquid, and then measured the mass of the flask and the liquid. The recorded measurements are shown in the table above. On the basis of this information, to how many significant figures should the density of the liquid be reported? a. 4 b. 6 c. 8 d. 3 e. 5

A. 4

If 87 g of K2SO4 (molar mass 174 g) is dissolved in enough water to make 250 mL of solution, what are the concentrations of potassium and sulfate ion respectively? a. 4.0 and 2.0 M b. 1.0 M and 2.0 M c. 0.0020 M and 0.0020 M d. 2.0 M and 2.0 M e. 2.0 M and 1.0 M

A. 4.0 and 2.0 M

A 0.20-molar solution of a weak monoprotic acid, HA, has a pH of 3.00. The ionization constant of this acid is a. 5.0 x 10^ ̄6 b. 2.0 x 10^ ̄7 c. 5.0 x 10^ ̄7 d. 2.0 x 10^ ̄3 e. 5.0 x 10^ ̄3

A. 5.0 x 10 ̄6

The isomerization of cyclopropane to propylene is a first-order process with a half-life of 19 minutes at 500 °C. The time it takes for the partial pressure of cyclopropane to decrease from 1.0 atmosphere to 0.125 atmosphere at 500 °C is closest to a. 57 minutes b. 38 minutes c. 152 minutes d. 190 minutes e. 76 minutes

A. 57 minutes

When 8.0 g of N2H4 (32 g mol-1) and 92 g of N2O4 (92 g mol-1) are mixed together and react according to the equation above, what is the maximum mass of H2O that can be produced? a. 9.0 g b. 72 g c. 144 g d. 36 g e. 18 g

A. 9.0 g

The equilibrium constant for the reaction represented by the equation above is greater than 1.0. Which of the following gives the correct relative strengths of the acids and bases in the reaction?

A. Acids: H2PO^4 ̄ > H2BO^3 ̄ Bases: HPO4^2 ̄ > HBO3^2 ̄

The energy required to form the transition state in a chemical reaction a. Activation energy b. Free energy c. Lattice energy d. Ionization energy e. Kinetic energy

A. Activation energy

The net ionic equation for the reaction between silver carbonate and hydrochloric acid is

A. Ag2CO3(s) + 2 H+ + 2 Cl ̄ --> 2AgCl(s) + H2O + CO(g)

Barium sulfate is LEAST soluble in a 0.01-molar solution of which of the following? a. Al2(SO4)3 b. BaCl2 c. Na2SO4 d. (NH4)2SO4 e. NH3

A. Al2(SO4)3

Assume that you have an "unknown" consisting of an aqueous solution of a salt that contains one of the ions listed below. Which ions must be absent on the basis of each of the following observations of the "unknown"? No precipitate is formed when a dilute solution of H2SO4 is added to a sample of the solution. a. Ba2+ d. Al3+ e. Cr2O72 ̄ c. NH4+ b. CO32 ̄

A. Ba2+

A 27.0-gram sample of an unknown hydrocarbon was burned in excess oxygen to form 88.0 grams of carbon dioxide and 27.0 grams of water. What is a possible molecular formula of the hydrocarbon? a. C4H6 b. C2H2 c. CH4 d. C4H3 e. C4H10

A. C4H6

Ascorbic acid, H2C6H6O6(s), is a diprotic acid with K1 = 7.9 X 10-5 and K2 = 1.6 X 10-12. In a 0.005 M aqueous solution of ascorbic acid, which of the following species is present in the lowest concentration? a. C6H6O6^2-(aq) b. HC6H6O6-(aq) c. H3O+(aq) d. H2C6H6O6(aq) e. H2O(l)

A. C6H6O6^2- (aq)

The proposed steps for a catalyzed reaction between Ce4+ and Tl+ are represented above. The products of the overall catalyzed reaction are a. Ce3+ and Tl3+ b. Tl3+ and Mn2+ c. Ce3+ and Mn3+ d. Ce3+ and Mn4+ e. Ce4+ and Tl+

A. Ce3+ and Tl3+

For the reaction A(g) B(g) + C(g), the equilibrium constant, Kp, is 2 x 10 ̄4 at 25 °C. A mixture of the three gases at 25 °C is placed in a reaction flask and the initial pressures are PA = 2 atmosphere, PB = 0.5 atmosphere, and PC = 1 atmosphere, At the instant of mixing, which of the following is true for the reaction as written? a. G° = 0 b. S = 0 c. G° < 0 d. G > 0 e. G < 0

A. G° = 0

Equal volumes of 0.10-molar H3PO4 and 0.20-molar KOH are mixed. After equilibrium is established, the type of ion an solution in largest concentration, other than the K+ ion, is a. HPO42 ̄ b. H2PO4 ̄ c. PO43 ̄ d. H3O+ e. OH ̄

A. HPO4^2 ̄

Some PCl3 and Cl2 are mixed in a container at 200 °C and the system reaches equilibrium according to the equation above. Which of the following causes an increase in the number of moles of PCl5 present at equilibrium? I. Decreasing the volume of the container II. Raising the temperature III. Adding a mole of He gas at constant volume a. I only b. II and III only c. I, II, and III d. II only e. I and III only

A. I only

Factors that affect the rate of a chemical reaction include which of the following? I. Frequency of collisions of reactant particles II. Kinetic energy of collisions of reactant particles III. Orientation of reactant particles during collisions a. I, II, and III b. II only c. II and III only d. I and II only e. I and III only

A. I, II, and III

The graph below shows the titration curve that results when 100. mL of 0.0250 M acetic acid is titrated with 0.100 M NaOH. Which of the following indicators is the best choice for this titration? a. Indicator: Phenolphthalein pH Range of Color Change: 8.2 - 10.0 b. Indicator: Methyl Orange pH Range of Color Change: 3.2 - 4.4 c. Indicator: Alizarin pH Range of Color Change: 11.0 -12.4 d. Indicator: Methyl Red pH Range of Color Change: 4.8 - 6.0 e. Indicator: Bromothymol Blue pH Range of Color Change: 6.1 - 7.6

A. Indicator: Phenolphthalein pH Range of Color Change: 8.2 - 10.0

The graph above shows the results of a study of the reaction of X with a large excess of Y to yield Z. The concentrations of X and Y were measured over a period of time. According to the results, which of the following can be concluded about the rate law for the reaction under the conditions studied? a. It is first order in [X]. b. The overall order of the reaction is 2. c. It is second order in [X]. d. It is first order in [Y]. e. It is zero order in [X].

A. It is first order in [X].

A compound contains 1.10 mol of K, 0.55 mol of Te, and 1.65 mol of O. What is the simplest formula of this compound? a. K2TeO3 b. KTe2O c. KTeO d. K2TeO6 e. K4TeO6

A. K2TeO3

The simplest formula for an oxide of nitrogen that is 36.8 percent nitrogen by weight is a. N2O3 b. N2O5 c. N2O d. NO2 e. NO

A. N2O3

All of the following species can function as Brönsted-Lowry bases in solution EXCEPT a. NH4+ b. H2O c. S2 ̄ d. HCO3 ̄ e. NH3

A. NH4+

The initial-rate data in the table above were obtained for the reaction represented below. What is the experimental rate law for the reaction?

A. Rate = k[NO][O2]2

Which of the following is a correct statement about reaction order? a. Reaction order can be determined only by experiment. b. Reaction order can be determined only from the coefficients of the balanced equation for the reaction. c. Reaction order increases with increasing temperature. d. Reaction order can only be a whole number. e. A second-order reaction must involve at least two different compounds as reactants.

A. Reaction order can be determined only by experiment.

Relatively slow rates of chemical reaction are associated with which of the following? a. Strong bonds in reactant molecules b. High temperature c. Low activation energy d. The presence of a catalyst e. High concentration of reactants

A. Strong bonds in reactant molecules

When dilute nitric acid was added to a solution of one of the following chemicals, a gas was evolved, This gas turned a drop of limewater, Ca(OH)2, cloudy, due to the formation of a white precipitate. The chemical was a. baking soda, NaHCO3 b. epsom salts, MgSO4. 7H2O c. household ammonia, NH3 d. table salt, NaCl e. bleach, 5% NaOCl

A. baking soda, NaHCO3

In liquid ammonia, the reaction represented above occurs. In the reaction NH4+ acts as a. the conjugate acid of NH3 b. a catalyst c. the oxidizing agent d. both an acid and a base e. the reducing agent

A. the conjugate acid of NH3

The diagram above represents a mixture of NO2(g) and N2O4(g) in a 1.0 L container at a given temperature. The two gases are in equilibrium according to the equation 2 NO2(g) N2O4(g). Which of the following must be true about the value of the equilibrium constant for the reaction at this temperature? a. K = 0 b. 0 < K < 1 c. K = 1 d. There is not enough information to determine the relative value of K. e. K > 1

B. 0 < K < 1

The reaction of silver metal and dilute nitric acid proceeds according to the equation above. If 0.10 mole of powdered silver is added to 10. milliliters of 6.0-molar nitric acid, the number of moles of NO gas that can be formed is a. 0.030 mole b. 0.015 mole c. 0.020 mole d. 0.045 mole e. 0.090 mole

B. 0.015 mole

Which of the following has the lowest conductivity? a. 0.1 M BaCl2 b. 0.1 M HF c. 0.1 M CuS04 d. 0.1 M KOH e. 0.1 M HNO3

B. 0.1 M HF

How many carbon atoms are contained in 2.8 g of C2H4? a. 6.0x10^24 b. 1.2 x 10^23 c. 1.2x10^24 d. 3.0x10^23 e. 6.0x10^23

B. 1.2 x 10^23

How many electrons are transferred in the reaction represented by the balanced equation above? a. 4 b. 10 c. 2 d. 8 e. 5

B. 10

The mass of element Q found in 1.00 mole of each of four different compounds is 38.0 grams, 57.0 grams, 76.0 grams, and 114 grams, respectively. A possible atomic weight of Q is a. 27.5 b. 19.0 c. 57.0 d. 38.0 e. 12.7

B. 19.0

In a saturated solution of Zn(OH)2 at 25oC, the value of [OH-] is 2.0 X 10-6 M. What is the value of the solubility-product constant, Ksp, for Zn(OH)2 at 25oC? a. 2.0 X 10^-6 b. 4.0 X 10^-18 c. 4.0 X 10^-12 d. 8.0 X 10^-18 e. 1.6 X 10^-17

B. 4.0 X 10^-18

When 70. milliliter of 3.0-molar Na2CO3 is added to 30. milliliters of 1.0-molar NaHCO3 the resulting concentration of Na+ is a. 2.0 M b. 4.5 M c. 7.0 M d. 2.4 M e. 4.0 M

B. 4.5 M

When a 1.00 gram sample of limestone was dissolved in acid, 0.38 grams of CO2 was generated. If the rock contained no carbonate other than CaCO3 , what was the percent of CaCO3 by mass in the limestone? a. 17% b. 86% c. 51% d. 64% e. 100%

B. 86%

A hydrocarbon gas with an empirical formula CH2 has a density of 1.88 grams per liter at 0°C and 1.00 atmosphere. A possible formula for the hydrocarbon is a. C4H8 b. C3H6 c. CH2 d. C5H10 e. C2H4

B. C3H6

Concentrations of colored substances are commonly measured by means of a spectrophotometer. Which of the following would ensure that correct values are obtained for the measured absorbance? I. There must be enough sample in the tube to cover the entire light path. II. The instrument must be periodically reset using a standard. III. The solution must be saturated. a. I, II, and III b. I and II only c. II only d. I only e. II and III only

B. I and II only

In the equilibrium represented above, the species that act as bases include which of the following? I. HSO4 ̄ II. H2O III. SO4^2 ̄ a. II only b. II and III c. I and III d. I and II e. III only

B. II and III

Appropriate laboratory procedures include which of the following? I. Rinsing a buret with distilled water just before filling it with the titrant for the first titration II. Lubricating glass tubing before inserting it into a stopper III. For accurate results, waiting until warm or hot objects have reached room temperature before weighing them a. I, II, and III b. II and III only c. I and II only d. I and III only e. II only

B. II and III only

A possible mechanism for the overall reaction represented above is the following. (1) NO(g) + NO(g) N2O2(g) ----> slow (2) N2O2(g) + O2(g) 2 NO2(g) ----> fast Which of the following rate expressions agrees best with this possible mechanism?

B. Rate = k[NO]2

According to the rate law for the reaction, an increase in the concentration of hydronium ion has what effect on this reaction? a. The rate of reaction decreases. b. The rate of reaction increases. c. The value of the equilibrium constant decreases. d. Neither the rate nor the value of the equilibrium constant is changed. e. The value of the equilibrium constant increases.

B. The rate of reaction increases.

The substance is at its normal freezing point at time a. t1 b. t2 c. t3 d. t4 e. t5

B. t2

When phenolphthalein is used as the indicator in a titration of an HCl solution with a solution of NaOH, the indicator undergoes a color change from clear to red at the endpoint of the titration. This color change occurs abruptly because a. phenolphthalein undergoes an irreversible reaction in basic solution b. the solution being titrated undergoes a large pH change near the end point of the titration c. OH ̄ acts as a catalyst for the decomposition of phenolphthalein d. phenolphehalein is involved in the rate-determining step of the reaction between H3O+ and OH ̄ e. phenolphthalein is a very strong acid that is capable of rapid dissociation

B. the solution being titrated undergoes a large pH change near the end point of the titration

A 360. mg sample of aspirin, C9H8O4, (molar mass 180. g), is dissolved in enough water to produce 200. mL of solution. What is the molarity of aspirin in a 50. mL sample of this solution? a. 0.0200 M b. 0.0800 M c. 0.0100 M d. 0.0400 M e. 0.00250 M

C. 0.0100 M

A 40.0 mL sample of 0.25 M KOH is added to 60.0 mL of 0.15 M Ba(OH)2. What is the molar concentration of OH- (aq) in the resulting solution? (Assume that the volumes are additive.) a. 0.19 M b. 0.40 M c. 0.28 M d. 0.55 M e. 0.10 M

C. 0.28 M

Commercial vinegar was titrated with NaOH solution to determine the content of acetic acid, HC2H3O2. For 20.0 milliliters of the vinegar 26.7 milliliters of 0.600-molar NaOH solution was required. What was the concentration of acetic acid in the vinegar if no other acid was present? a. 1.60 M b. 0.450 M c. 0.800 M d. 0.200 M e. 0.600 M

C. 0.800 M

Mass of an empty container = 3.0 grams Mass of the container plus the solid sample = 25.0 grams Volume of the solid sample = 11.0 cubic centimeters The data above were gathered in order to determine the density of an unknown solid. The density of the sample should be reported as a. 2.27 g/cm3 b. 0.50 g/cm3 c. 2.00 g/cm3 d. 0.5 g/cm3 e. 2.0 g/cm3

C. 2.00 g/cm3

If the acid dissociation constant, Ka, for an acid HA is 8 x 10 ̄4 at 25°C, what percent of the acid is dissociated in a 0.50-molar solution of HA at 25 °C? a. 0.2% b. 0.08% c. 4% d. 2% e. 1%

C. 4%

Gaseous cyclobutene undergoes a first order reaction to form gaseous butadiene. At a particular temperature, the partial pressure of cyclobuten in the reaction vessel drops to one-eighth its original value in 124 seconds. What is the half-life for this reaction at this temperature? a. 124 s b. 62.0 s c. 41.3 s d. 15.5 s e. 31.0 s

C. 41.3 s

A student wishes to prepare 2.00 liters of 0.100-molar KIO3 (molecular weight 214). The proper procedure is to weigh out a. 21.4 grams of KIO3 and add H2O until the final homogeneous solution has a volume of 2.00 liters b. 21.4 grams fo KIO3 and add 2.00 liters of H2O c. 42.8 grams of KIO3 and add H2O until the final homogeneous solution has a volume of 2.00 liters d. 42.8 grams of KIO3 and add 2.00 liters of H2O e. 42.8 grams of KIO3 and add 2.00 kilograms of H2O

C. 42.8 grams of KIO3 and add H2O until the final homogeneous solution has a volume of 2.00 liters

How many moles of O2 are required to oxidize 1 mole of CH3CH2COOH according to the reaction represented above? a. 9/2 moles b. 5/2 moles c. 7/2 moles d. 2 moles e. 3 moles

C. 7/2 moles

If 87.5 percent of a sample of pure 131I decays in 24 days, what is the half-life of 131I? a. 21 days b. 12 days c. 8 days d. 14 days e. 6 days

C. 8 days

Which of the following represents acceptable laboratory practice? a. Placing a hot object on a balance pan b. Diluting a solution in a volumetric flask to its final concentration with hot water c. Adding a weighed quantity of solid acid to a titration flask wet with distilled water d. Using 10 mL of standard strength phenolphthalein indicator solution for titration of 25 mL of acid solution e. Using distilled water for the final rinse of a buret before filling it with standardized solution

C. Adding a weighed quantity of solid acid to a titration flask wet with distilled water

A solution of calcium hypochlorite, a common additive to swimming pool water is a. Acidic because the acid HOCl is formed b. Acidic because of the hydrolysis of the Ca2+ ions c. Basic because of the hydrolysis of the OClion d. Basic because Ca(OH)2 is a weak insoluble base e. Neutral if the concentration is kept below 0.1 molar

C. Basic because of the hydrolysis of the OCl ion

How can 100. mL of sodium hydroxide solution with a pH of 13.00 be converted to a sodium hydroxide solution with a pH of 12.00? a. By diluting the solution with distilled water to a total volume of 200 mL b. By adding 100. mL of 0.10 M HCl c. By diluting the solution with distilled water to a total volume of 1.00 L d. By diluting the solution with distilled water to a total volume of 108 mL e. By adding 100. mL of 0.10 M NaOH

C. By diluting the solution with distilled water to a total volume of 1.00 L

The reaction represented above has an equilibrium constant equal to 3.7 X 104. Which of the following can be concluded from this information? a. HCN (aq) is a stronger acid than HC2H3O2 (aq). b. The equilibrium constant will increase with an increase in temperature. c. CN-(aq) is a stronger base than C2H3O2-(aq). d. The pH of a solution containing equimolar amounts of CN- (aq) and HC2H3O2 (aq) is 7.0. e. The conjugate base of CN-(aq) is C2H3O2-(aq).

C. CN- (aq) is a stronger base than C2H3O2- (aq).

Which, if any, of the following species is in the greatest concentration in a 0.100-molar solution of H2SO4 in water? a. All species are in equilibrium and therefore have the same concentrations. b. SO4 2 ̄ ions c. H3O+ ions d. H2SO4 molecules e. HSO4 ̄ ions

C. H3O+ ions

At 25°C and 1 atm, is a strong electrolyte in aqueous solution a. H2 b. NH3 c. HBr d. H2S e. BH3

C. HBr

When hafnium metal is heated in an atmosphere of chlorine gas, the product of the reaction is found to contain 62.2 percent Hf by mass and 37.4 percent Cl by mass. What is the empirical formula for this compound? a. HfCl2 b. HfCl4 c. HfCl3 d. Hf2Cl3 e. HfCl

C. HfCl3

Which of the following is the correct equilibrium expression for the hydrolysis of CO3^2 ̄ ?

C. K = ( [HCO3 ̄] [OH ̄] ) / [CO3^2-)

A sample of 61.8 g of H3BO3, a weak acid, is dissolved in the 1,000 g of water to make a 1.0-molal solution. Which of the following would be the best procedure to determine the molarity of the solution? (Assume no additional information is available.) a. Measurement of the pH with a pH meter b. Determination of the boiling point of the solution c. Measurement of the total volume of the solution d. Titration of the solution with standard acid e. Measurement of the specific heat of the solution

C. Measurement of the total volume of the solution

A 0.10 M aqueous solution of sodium sulfate, Na2SO4, is a better conductor of electricity than a 0.10 M aqueous solution of sodium chloride, NaCl. Which of the following best explains this observation? a. To prepare a given volume of 0.10 M solution, the mass of Na2SO4 needed is more than twice the mass of NaCl needed. b. Na2SO4 has a higher molar mass than NaCl has. c. More moles of ions are present in a given volume of 0.10 M Na2SO4 than in the same volume of 0.10 M NaCl. d. The degree of dissociation of Na2SO4 in solution is significantly greater than that of NaCl e. Na2SO4 is more soluble in water than NaCl is.

C. More moles of ions are present in a given volume of 0.10 M Na2SO4 than in the same volume of 0.10 M NaCl.

Salts containing which of the following ions are generally insoluble in cold water? a. nitrate b. acetate c. phosphate d. potassium e. ammonium

C. Phosphate

Forms monatomic ions with 2 ̄ charge in solutions a. Mg b. F c. S d. Ar e. Mn

C. S

After completing an experiment to determine gravimetrically the percentage of water in a hydrate, a student reported a value of 38 percent. The correct value for the percentage of water in the hydrate is 51 percent. Which of the following is the most likely explanation for this difference? a. The crucible was not heated to constant mass before use. b. The amount of the hydrate sample used was too small. c. The dehydrated sample absorbed moisture after heating. d. Excess heating caused the dehydrated sample to decompose. e. Strong initial heating caused some of the hydrate sample to spatter out of the crucible.

C. The dehydrated sample absorbed moisture after heating.

Forms a compound having the formula KXO4A student pipetted five 25.00-milliliter samples of hydrochloric acid and transferred each sample to an Erlenmeyer flask, diluted it with distilled water, and added a few drops of phenolphthalein to each. Each sample was then titrated with a sodium hydroxide solution to the appearance of the first permanent faint pink color. The following results were obtained. Volumes of NaOH Solution First Sample..................35.22 mL Second Sample..............36.14 mL Third Sample.................36.13 mL Fourth Sample..............36.15 mL Fifth Sample..................36.12 mL Which of the following is the most probable explanation for the variation in the student's results? a. The student misread a 5 for a 6 on the burette when the first sample was titrated. b. The student added too little indicator to the first sample. c. The pipette was not rinsed with the HCI solution. d. A different amount of water was added to the first sample. e. The burette was not rinsed with NaOH solution.

C. The pipette was not rinsed with the HCI solution.

Which of the following is a correct interpretation of the results of Rutherford's experiments in which gold atoms were bombarded with alpha particles? a. Atoms have equal numbers of positive and negative charges. b. Neutrons are at the center of an atom. c. The positive charge of an atom is concentrated in a small region. d. Electrons in atoms are arranged in shells. e. Neutrons and protons in atoms have nearly equal mass.

C. The positive charge of an atom is concentrated in a small region.

When 100 mL of 1.0 M Na3PO4 is mixed with 100 mL of 1.0 M AgNO3, a yellow precipitate forms when [Ag+] becomes negligibly small. Which of the following is a correct listing of the ions remaining in solution in order of increasing concentration? a. [Na+] < [NO3-] < [PO43-] b. [NO3-] < [PO43-] < [Na+] c. [PO43-] < [NO3-] < [Na+] d. [Na+] < [PO43-] < [NO3-] e. [PO43-] < [Na+] < [NO3-]

C. [PO4^3-] < [NO3-] < [Na+]

True statements about the reaction represented above include which of the following? I. Cu(s) acts as an oxidizing agent. II. The oxidation state of nitrogen changes from +5 to +2. III. Hydrogen ions are oxidized to form H2O(l). a. II and III b. II only c. I and II d. III only e. I only

D

What is the standard enthalpy change for the reaction represented above? a. +773 kJ b. -19 kJ c. -147 kJ d. -607 kJ e. +19 kJ

D. -607 kJ

According to the balanced equation above, how many moles of ClO2-(aq) are needed to react completely with 20. mL of 0.20 M KMnO4 solution? a. 0.013 mol b. 0.030 mol c. 0.0075 mol d. 0.0030 mol e. 0.0053 mol

D. 0.0030 mol

What is the final concentration of barium ions, [Ba2+], in solution when 100. mL of 0.10 M BaCl2(aq) is mixed with 100. mL of 0.050 M H2SO4(aq)? a. 0.10 M b. 0.012 M c. 0.075 M d. 0.025 M e. 0.00 M

D. 0.025 M

How many moles of NaF must be dissolved in 1.00 liter of a saturated solution of PbF2 at 25 °C to reduce the [Pb2+] to 1 x 10 ̄ 6 molar? (Ksp of PbF2 at 25 °C = 4.0 x 10 ̄8) a. 0.40 mole b. 0.10 mole c. 0.020 mole d. 0.20 mole e. 0.040 mole

D. 0.20 mole

What mass of Au is produced when 0.0500 mol of Au2S3 is reduced completely with excess H2? a. 39.4 g b. 9.85 g c. 48.9 g d. 19.7 g e. 24.5 g

D. 19.7 g

The atomic mass of copper is 63.55. Given that there are only two naturally occurring isotopes of copper, 63Cu and 65Cu, the natural abundance of the 65Cu isotope must be approximately a. 70% b. 90% c. 10% d. 25% e. 50%

D. 25%

The solubility of CuI is 2 x 10 ̄6 molar. What is the solubility product constant, Ksp, for CuI? a. 2 x 10^ ̄6 b. 1.4 x 10^ ̄3 c. 2 x 10^ ̄12 d. 4 x 10^ ̄12 e. 8 x 10^ ̄18

D. 4 x 10^ ̄ 12

How many grams of calcium nitrate, Ca(NO3)2, contains 24 grams of oxygen atoms? a. 164 grams b. 62 grams c. 50. grams d. 41 grams e. 96 grams

D. 41 grams

Which of the following must be true for a reaction for which the activation energy is the same for both the forward and the reverse reactions? a. A catalyst is present. b. The reaction order can be obtained directly from the balanced equation. c. The reaction order is zero. d. H for the reaction is zero. e. S for the reaction is zero.

D. H for the reaction is zero.

Which of the following changes to the equilibrium system represented above will increase the quantity of HI(g) in the equilibrium mixture? I. Adding H2(g) II. Increasing the temperature III. Decreasing the pressure a. I, II, and III b. I only c. II and III only d. I and II only e. III only

D. I and II only

Which of the following changes alone would cause a decrease in the value of Keq for the reaction represented above? a. Decreasing the volume of the reaction vessel b. Adding a catalyst c. Increasing the volume of the reaction vessel d. Increasing the temperature e. Decreasing the temperature

D. Increasing the temperature

On the basis of the solubility curves shown above, the greatest percentage of which compound can be recovered by cooling a saturated solution of that compound from 90 degrees to 30 degrees? a. K2CrO4 b. Ce2(SO4)3 c. NaCl d. KNO3 e. K2SO4

D. KNO3

Each of the following can act as both a Brönsted acid and a Brönsted base EXCEPT a. HCO3 ̄ b. HS ̄ c. H2O d. NH4+ e. H2PO4 ̄

D. NH4+

A reaction was observed for 20 days and the percentage of the reactant remaining after each day was recorded in the table above. Which of the following best describes the order and the half-life of the reaction? a. Reaction Order: Second, Half-life (days): 6 b. Reaction Order: Second, Half-life (days): 10 c. Reaction Order: First, Half-life (days): 10 d. Reaction Order: First, Half-life (days): 3 e. Reaction Order: Second, Half-life (days): 3

D. Reaction Order: First, Half-life (days): 3

Which of the following best describes the role of the spark from the spark plug in an automobile engine? a. The spark decreases the energy of activation for the slow step. b. The spark provides a more favorable activated complex for the combustion reaction. c. The spark provides the heat of vaporization for the volatile hydrocarbon. d. The spark supplies some of the energy of activation for the combustion reaction. e. The spark increases the concentration of the volatile reactant.

D. The spark supplies some of the energy of activation for the combustion reaction.

All of the halogens in their elemental form at 25oC and 1 atm are a. diatomic molecules b. odorless c. gases d. colorless e. conductors of electricity

D. colorless

The cooling curve above shows how the temperature of a sample varies with time as the sample goes through phase changes. The sample starts as a gas, and heat is removed at a constant rate. At which time does the sample contain the most liquid? a. t1 b. t2 c. t3 d. t4 e. t5

D. t4

What is the molar solubility in water of Ag2CrO4? (The Ksp for Ag2CrO4 is 8 X 10-12.)

E

The oxidation state that is common to aqueous ions of Fe, Mn, and Zn is a. +1 b. +3 c. +5 d. +4 e. +2

E. +2

If 200. mL of 0.60 M MgCl2(aq) is added to 400. mL of distilled water, what is the concentration of Mg2+(aq) in the resulting solution? (Assume volumes are additive.) a. 0.30 M b. 0.60 M c. 1.2 M d. 0.40 M e. 0.20 M

E. 0.20 M

If 0.40 mol of H2 and 0.15 mol of O2 were to react completely as possible to produce H2O, what mass of reactant would remain? a. 4.0 g of O2 b. 4.4 g of O2 c. 0.40 g of H2 d. 3.2 g of O2 e. 0.20 g of H2

E. 0.20 g of H2

What number of moles of O2 is needed to produce 14.2 grams of P4O10 from P? (Molecular weight P4O10 = 284) a. 0.0500 mole b. 0.500 mole c. 0.125 mole d. 0.0625 mole e. 0.250 mole

E. 0.250 mole

A 1.0 L sample of an aqueous solution contains 0.10 mol of NaCl and 0.10 mol of CaCl2. What is the minimum number of moles of AgNO3 that must be added to the solution in order to precipitate all of the Cl- as AgCl (s)? (Assume that AgCl is insoluble.)

E. 0.30 mol

The pH of 0.1-molar ammonia is approximately a. 7 b. 1 c. 14 d. 4 e. 11

E. 11

The pH of a solution prepared by the addition of 10. mL of 0.002 M KOH(aq) to 10. mL of distilled water is closest to a. 3 b. 4 c. 12 d. 10 e. 11

E. 11

The volume of distilled water that should be added to 10.0 mL of 6.00 M HCl(aq) in order to prepare a 0.500 M HCl(aq) solution is approximately a. 60.0 mL b. 50.0 mL c. 120. mL d. 100. mL e. 110. mL

E. 110. mL

The weight of H2SO4 (molecular weight 98.1) in 50.0 milliliters of a 6.00-molar solution is a. 300. grams b. 12.0 grams c. 3.10 grams d. 294 grams e. 29.4 grams

E. 29.4 grams

Propane gas, C3H8, burns in excess oxygen gas. When the equation for this reaction is correctly balanced and all coefficients are reduced to their lowest whole-number term, the coefficient for O2 is a. 7 b. 10 c. 4 d. 22 e. 5

E. 5

According to the balanced equation above, how many moles of HI would be necessary to produce 2.5 mol of I2, starting with 4.0 mol of KMnO4 and 3.0 mol of H2SO4? a. 20. b. 2.5 c. 8.0 d. 10. e. 5.0

E. 5.0

At a certain temperature, the value of the equilibrium constant, K, for the reaction represented above is 2.0 X 105. What is the value of K for the reverse reaction at the same temperature? a. 5.0 X 10^-4 b. 2.0 X 10^-5 c. -2.0 X 10^-5 d. 5.0 X 10^-5 e. 5.0 X 10^-6

E. 5.0 X 10^-6

What is the H+ (aq) concentration in 0.05 M HCN (aq)? The Ka for HCN is 5.0 X 10-10.) a. 5.0 X 10^-4 M b. 2.5 X 10^-11 M c. 2.5 X 10^-10 M d. 5.0 X 10^-10 M e. 5.0 X 10^-6 M

E. 5.0 X 10^-6 M

A measured mass of an unreactive metal was dropped into a small graduated cylinder half filled with water. The following measurements were made. Mass of metal = 19.611 grams Volume of water before addition of metal = 12.4 milliliters Volume of water after addition of metal = 14.9 milliliters The density of the metal should be reported as a. 8 grams per mL b. 7.84 grams per mL c. 7.844 grams per mL d. 7.8444 grams per mL e. 7.8 grams per mL

E. 7.8 grams per mL

The rate of a certain chemical reaction between substances M and N obeys the rate law above. The reaction is first studied with [M] and [N] each 1 X 10-3 molar. If a new experiment is conducted with [M] and [N] each 2 X 10-3 molar, the reaction rate will increase by a factor of a. 6 b. 2 c. 4 d. 16 e. 8

E. 8

It is suggested that SO2 (molar mass 64 grams), which contributes to acid rain, could be removed from a stream of waste gases by bubbling the gases through 0.25-molar KOH, thereby producing K2SO3 . What is the maximum mass of SO2 that could be removed by 1,000 liters of the KOH solution? a. 16 kg b. 40. kg c. 20. kg d. 4.0 kg e. 8.0 kg

E. 8.0 kg

Which of the following conclusions can be drawn from J. J. Thomson's cathode ray experiments? a. Atoms contain protons, neutrons, and electrons. b. Practically all the mass of an atom is contained in its nucleus. c. No two electrons in one atom can have the same four quantum numbers. d. Atoms have a positively charged nucleus surrounded by an electron cloud. e. Atoms contain electrons.

E. Atoms contain electrons.

If some solid sodium solid hydroxide is added to a solution that is 0.010-molar in (CH3)3CCl and 0.10-molar in NaOH, which of the following is true? (Assume the temperature and volume remain constant.) a. The reaction rate increases but k remains the same. b. Both the reaction rate and k decrease. e. Both the reaction rate and k remain the same. c. The reaction rate decreases but k remains the same. d. Both the reaction rate and k increase.

E. Both the reaction rate and k remain the same.

In which of the following compounds is the mass ratio of chromium to oxygen closest to 1.62 to 1.00 ? a. Cr2O3 b. CrO3 c. Cr2O d. CrO e. CrO2

E. CrO2

Which of the following techniques is the most appropriate for the recovery of solid KNO3 from an aqueous solution of KNO3? a. Paper chromatography b. Filtrations c. Titration d. Electrolysis e. Evaporation to dryness

E. Evaporation to dryness

Appropriate uses of a visible-light spectrophotometer include which of the following? I. Determining the concentration of a solution of Cu(NO3)2 II. Measuring the conductivity of a solution of KMnO4 III. Determining which ions are present in a solution that may contain Na+, Mg2+, Al3+ a. II only b. III only c. I and III only d. I and II only e. I only

E. I only

To determine the molar mass of a solid monoprotic acid, a student titrated a weighed sample of the acid with standardized aquesous NaOH. Which of the following could explain why the student obtained a molar mass that was too LARGE? I. Failure to rinse all acid from the weighing paper into the titration vessel. II Addition of more water than was needed to dissolve the acid III Addition of some base beyond the equivalence point. a. I, II, and III b. III only c. II and III only d. I and II only e. I only

E. I only

Which element exhibits the greatest number of different oxidation states? a. Rb b. La c. Mg d. O e. N

E. N

A 1-molar solution of which of the following salts has the highest pH? a. NH4Cl b. NaNO3 c. NaHSO4 d. Na2SO4 e. Na2CO3

E. Na2CO3

When a hydrate of Na2CO3 is heated until all the water is removed, it loses 54.3 percent of its mass. The formula of the hydrate is a. Na2CO3 . 3 H2O b. Na2CO3 . 5 H2O c. Na2CO3 . H2O d. Na2CO3 . 10 H2O e. Na2CO3 . 7 H2O

E. Na2CO3 . 7 H2O

What part of the curve corresponds to the optimum buffer action for the acetic acid/acetate ion pair? a. Point Z b. Along all of section WY c. Along all of section YZ d. Point X e. Point V

E. Point V

A compound contains 30. percent sulfur and 70. percent fluorine by mass. The empirical formula of the compound is a. SF2 b. SF c. SF6 d. S2F e. SF4

E. SF4

In which of the following species does sulfur have the same oxidation number as it does in H2SO4? a. S8 b. H2SO3 c. S2O3^2- d. S^2- e. SO2Cl2

E. SO2Cl2

As the number of oxygen atoms increases in any series of oxygen acids, such as HXO, HXO2, HXO3, ...., which of the following is generally true? a. The acid strength varies unpredictably. b. The acid strength decreases only if X is a nonmetal. c. The acid strength decreases whether X is a nonmetal or a metal. d. The acid strength decreases only if X is a metal. e. The acid strength increases.

E. The acid strength increases.

After the equilibrium represented above is established, some pure O2 (g) is injected into the reaction vessel at constant temperature. After equilibrium is reestablished, which of the following has a lower value compared to its value at the original equilibrium? a. The amount of SO3 (g) in the reaction vessel b. The total pressure in the reaction vessel c. The amount of O2 (g) in the reaction vessel d. Keq for the reaction e. The amount of SO2 (g) in the reaction vessel

E. The amount of SO2 (g) in the reaction vessel

In the titration of a weak acid of unknown concentration with a standard solution of a strong base, a pH meter was used to follow the progress of the titration. Which of the following is true for this experiment? a. The [H+] at the equivalence point equals the ionization constant of the acid. b. The pH at the equivalence point depends on the indicator used. e. The graph of pH versus volume of base added rises gradually at first and then much more rapidly. c. The pH is 7 at the equivalence point. d. The graph of pH versus volume of base added shows no sharp rise.

E. The graph of pH versus volume of base added rises gradually at first and then much more rapidly.

Which of the following best describes what happens to the substance between t4 and t5? a. The average intermolecular distance is decreasing. b. The solid and liquid phases coexist in equilibrium. e. The molecules are leaving the liquid phase. c. The vapor pressure of the substance is decreasing. d. The temperature of the substance is increasing.

E. The molecules are leaving the liquid phase.

The cooling curve for a pure substance as it changes from a liquid to a solid is shown above. The solid and liquid coexist at a. no point on the curve b. all points on the curve between R and T e. all points on the curve between Q and S c. point Q only d. point R only

E. all points on the curve between Q and S

When the concentration of substance B in the reaction above is doubled, all other factors being held constant, it is found that the rate of the reaction remains unchanged. The most probable explanation for this observation is that a. the reactant with the smallest coefficient in the balanced equation generally has little or no effecton the rate of the reaction b. substance B is not involved in any of the steps in the mechanism of the reaction c. the order of the reaction with respect to substance B is 1 d. substance B is probably a catalyst, and as such, its effect on the rate of the reaction does not depend on its concentration e. substance B is not involved in the rate-determining step of the mechanism, but is involved in subsequent steps

E. substance B is not involved in the rate-determining step of the mechanism, but is involved in subsequent steps

__________________________________________________________________________________________________

_______________________________________________________________________________

CH4(g) + 2 O2(g) CO2(g) + 2 H2O(l); H = - 889.1 kJ Hf° H2O(l) = - 285.8 kJ / mole Hf° CO2(g) = - 393.3 kJ / mole What is the standard heat of formation of methane, Hf° CH4(g), as calculated from the data above? a. -75.8 kJ/mole b. 75.8 kJ/mole c. -210.0 kJ/mole d. 210.0 kJ/mole e. -107.5 kJ/mole

a. -75.8 kJ/mole

How many mL of 10.0 M HCl are needed to prepare 500. mL of 2.00 M HCl? a. 100. mL b. 20.0 mL c. 10.0 mL d. 200. mL e. 1.00 mL

a. 100 mL

Oxalic acid, H2C2O4, is a diprotic acid with K1 = 5.36 x 10 ̄2 and K2 = 5.3 x 10 ̄5. For the reaction above, what is the equilibrium constant? a. 2.8 x 10^ ̄6 b. 1.9 x 10^ ̄10 c. 1.9 x 10^ ̄13 d. 5.36 x 10^ ̄2 e. 5.3 x 10^ ̄5

a. 2.8 x 10^ ̄6

When the equation above is balanced and all coefficients are reduced to lowest whole-number terms, what is the coefficient for H3PO4(l)? a. 4 b. 3 c. 5 d. 1 e. 2

a. 4

Approximately what mass of CuSO4•5H2O (250 g mol-1) is required to prepare 250 mL of 0.10 M copper(II) sulfate solution? a. 6.2 g b. 85 g c. 34 g d. 4.0 g e. 140 g

a. 6.2 g

The solution with the lowest pH a. HCl and NaCl b. NH3 and HC2H3O2 (acetic acid) c. NaOH and NH3 d. H3PO4 and NaH2PO4 e. NH3 and NH4Cl

a. HCL and NaCl

Reacts with water to form a strong base a. Lithium b. Bromine c. Flourine d. Uranium e. Nickel

a. Lithium

Which of the following statements regarding the reaction represented by the equation above is correct? a. The oxidation number of iodine changes from -1 to 0. b. MnO4 ̄ is oxidized by iodide ion. c. Iodide ion is oxidized by hydroxide ion. d. The oxidation number of manganese changes from +7 to +2. e. The oxidation number of manganese remains the same.

a. The oxidation number of iodine changes from -1 to 0.

Ionization Constants CH3COOH = 1.8 x 10 ̄5 NH3 = 1.8 x 10 ̄5 H2CO3; K1 = 4 x 10 ̄7 H2CO3; K2 = 4 x 10 ̄11 A solution prepared to be initially 1 M in Na2CO3 and 1 M in CH3COONa a. a solution with a pH greater than 7 that is not a buffer solution b. a buffer solution with a pH between 4 and 7 c. a solution with a pH of 7 d. a solution with a pH less than 7 that is not a buffer solution e. a buffer solution with a pH between 7 and 10

a. a solution with a pH greater than 7 that is not a buffer solution

The net ionic equation for the reaction that occurs during the titration of nitrous acid with sodium hydroxide is

b

For the reaction of ethylene represented above, H is -1,323 kJ. What is the value of H if the combustion produced liquid water H2O(l) ? (H for the phase change H2O(g) H2O(l) is -44 kJ mol1). a. -1,323 kJ b. -1,411 kJ c. -1,367 kJ d. -1,279 kJ e. -1,235 kJ

b. -1,411 KJ

When the skeleton equation above is balanced and all coefficients reduced to their lowest whole-number terms. what is the coeficient for H+ ? a. 8 b. 10 c. 6 d. 9 e. 4

b. 10

An oxidation-reduction reaction that is also a synthesis reaction.

b. 2Mg(s) + O2(g) ---> 2MgO(s)

If 1 mole of O2 oxidizes Fe(OH)2 according to the reaction represented above, how many moles of Fe(OH)3 can be formed? a. 6 b. 4 c. 2 d. 5 e. 3

b. 4

What volume of 0.150-molar HCl is required to neutralize 25.0 mililiters of 0.120-molar Ba(OH)2? a. 30.0 mL b. 40.0 mL c. 60.0 mL d. 80.0 mL e. 20.0 mL

b. 40.0 mL

When the equation above is correctly balanced and all coefficients are reduced to lowest whole-number terms, the coefficient for H+ (aq) is a. 2 b. 8 c. 6 d. 4 e. 14

b. 8

Consider the equilibrium above. Which of the following changes will increase the concentration of HgI4^2 ̄? a. Increasing the concentration of OH ̄ b. Adding 6 M HNO3 c. Increasing the mass of HgO present d. Increasing the temperature e. Adding a catalyst

b. Adding 6 M HNO3

True for the combustion of liquid pentane, C5H12(l) to form H2O(g) and CO2(g) at 1 atm. a. H < 0, S < 0 b. H < 0, S > 0 c. H > 0, S > 0 d. H = 0, S < 0 e. H > 0, S < 0

b. H < 0, S > 0

Acid Acid Dissociation Constant, Ka H3PO4 7 x 10 ̄3 H2PO4 ̄ 8 x 10 ̄8 HPO4 . 2 ̄ 5 x 10 ̄13 On the basis of the information above, a buffer with a pH = 9 can best be made by using a. pure NaH2PO4 b. H2PO4 ̄ + HPO42 ̄ c. H3PO4 + H2PO4 ̄ d. HPO42 ̄ + PO43 ̄ e. H2PO4 ̄ + PO43 ̄

b. H2PO4 ̄ + HPO42 ̄

Which of the following acids can be oxidized to form a stronger acid? a. HNO3 b. H2SO3 c. H3PO4 d. H3BO3 e. H2CO3

b. H2SO3

Ionization Constants CH3COOH = 1.8 x 10 ̄5 NH3 = 1.8 x 10 ̄5 H2CO3; K1 = 4 x 10 ̄7 H2CO3; K2 = 4 x 10 ̄11 A solution prepared to be initially 1 M in NaCl and 1 M in HCl. a. a buffer solution with a pH between 7 and 10 b. a solution with a pH less than 7 that is not a buffer solution c. a buffer solution with a pH between 4 and 7 d. a solution with a pH of 7 e. a solution with a pH greater than 7 that is not a buffer solution

b. a solution with a pH less than 7 that is not a buffer solution

At 25 °C the solubility product constant, Ksp, for MnS in 5 x 10 ̄15 and the acid dissociation constants K1 and K2 for H2S are 1 x 10 ̄7 and 1 x 10 ̄ 13, respectively. What is the equilibrium constant for the reaction represented by the equation above at 25 °C? a. 5 x 10^ ̄15 / 1 x 10^ ̄7 b 1 x 10^ ̄20 / 5 x 10^ ̄15 c. 5 x 10^ ̄15 / 1 x 10^ ̄20 d. 1 x 10 ̄^7/ 5 x 10^ ̄20 e. 1 x 10^ ̄13 / 5 x 10^ ̄15

c

How many milliliters of 11.6-molar HCl must be diluted to obtain 1.0 liter of 3.0-molar HCl? a. 3.9 mL b. 35 mL c. 260 mL d. 3,900 mL e. 1,000 mL

c. 260 mL

Which of the following shows the correct number of protons, neutrons, and electrons in a neutral cesium-134 atom? a. 79 protons, 55 neutrons, 79 electrons b. 55 protons, 79 neutrons, 79 electrons c. 55 protons, 79 neutrons, 55 electrons d. 134 protons, 55 neutrons, 134 electrons e. 55 protons, 55 neutrons, 55 electrons

c. 55 protons, 79 neutrons, 55 electrons

The point at which the concentration of the weak acid and its conjugate base are approximately equal. a. A b. B c. C d. D e. E

c. C

The point at which the moles of the added strong base are equal to the moles of the weak acid initially present a. A b. B c. C d. D e. E

c. C

Which of the following does NOT behave as an electrolyte when it is dissolved in water? a. Sodium acetate, CH3COONa b. HI c. CH3OH d. NH4Br e. K2CO3

c. CH3OH

When the reaction represented by the equation above is at equilibrium at 1 atm and 25oC, the ratio can be increased by doing which of the following? a. Adding acid b. Diluting the solution with distilled water c. Decreasing the temperature d. Adding a catalyst e. Bubbling neon gas through the solution

c. Decreasing the temperature

The energy diagram for the reaction X + Y Z is shown above. The addition of a catalyst to this reaction would cause a change in which of the indicated energy differences? a. I, II, and III b. II only c. I and II only d. I only e. III only

c. I and II only

Which of the following represents a pair of isotopes? a. I. Atomic Number: 6, Mass Number: 14 II. Atomic Number: 7, Mass Number, 14 b. I. Atomic Number: 6, Mass Number: 14 II. Atomic Number: 14, Mas Number: 28 c. I. Atomic Number: 7, Mass Number: 13 II. Atomic Number: 7, Mass Number: 14 d. I. Atomic Number: 8, Mass Number: 16 II. Atomic Number: 16, Mass Number: 20 e. I. Atomic Number: 6, Mass Number: 7 II. Atomic Number: 14, Mass Number: 14

c. I. Atomic Number: 7, MassNumber: 13II. Atomic Number: 7, Mass Number: 14

A sample of 10.0 mol of butyric acid, HC4H7O2, a weak acid, is dissolved in 1000.g of water to make a 10.0-molal solution. Which of the following would be the best method to determine the molarity of the solution? (In each case, assume that no additional information is available.) a. Determination of the freezing point of the solution b. Measurement of the pH with a pH meter c. Measurement of the total volume of the solution d. Titration of the solution with standard acid. e. Measurement of the electrical conductivity of the solution.

c. Measurement of the total volume of the solution

The most nearly neutral solution a. NH3 and NH4Cl b. NaOH and NH3 c. NH3 and HC2H3O2 (acetic acid) d. H3PO4 and NaH2PO4 e. HCl and NaCl

c. NH3 and HC2H3O2 (acetic acid)

Step 1) N2H2O2 N2HO2 ̄ + H+ (fast equilibrium) Step 2) N2HO2 ̄ N2O + OH ̄ (slow) Step 3) H+ + OH ̄ H2O (fast) Nitramide, N2H2O2, decomposes slowly in aqueous solution. This decomposition is believed to occur according to the reaction mechanism above. The rate law for the decomposition of nitramide that is consistent with this mechanism is given by which of the following? a. Rate = (k [N2H2O2]) / [N2HO2 ̄] b. Rate = k [N2H2O2] [H+] c. Rate = (k [N2H2O2]) / [H+] d. Rate = k [N2H2O2] e. Rate = k [N2H2O2] [OH ̄]

c. Rate = (k [N2H2O2]) / [H+]

A combustion reaction

d

At 25 degrees C, aqueous solutions with a pH of 8 have a hydroxide ion concentration, [OH-], of a. 1 X 10^-14 M b. 1 X 10^-8 M c. 1 M d. 1 X 10^-6 M e. 8 M

d. 1 x 10^-6 M

When the equation above is balanced and all coefficients are reduced to their lowest whole-number terms, the coefficient for O2 (g) is a. 7 b. 6 c. 14 d. 12 e. 28

d. 12

The table above shows the results from a rate study of the reaction X + Y à Z. Starting with known concentrations of X and Y in experiment 1, the rate of formation of Z was measured. If the reaction was first order with respect to X and second order with respect to Y, the initial rate of formation of Z in experiment 2 would be a. R/4 b. 4R c. R/2 d. 2R e. R

d. 2R

When the equation above is balanced and all coefficients reduced to lowest whole number terms, the coefficient for OH- (aq) is a. 4 b. 6 c. 1 d. 3 e. 2

d. 3

The reaction mixture represented above is at equilibrium at 298 K, and the molar concentrations are [X] = 2.0 M, [Y] = 0.5 M, and [Z] = 4.0 M. What is the value of the equilibrium constant for the reaction at 298 K? a. 0.50 b. 2.0 c. 16 d. 32 e. 4.0

d. 32

When the equation above is balanced with lowest whole-number coefficients, the coefficient for OH ̄ is a. 7 b. 4 c. 5 d. 6 e. 2

d. 6

Correct procedures for a titration include which of the following? I Draining a pipet by touching the tip to the side of the container used for the titration II Rinsing the buret with distilled water just before filling it with the liquid to be titrated. III Swirling the soluiton frequently during the titration. a. II only b. II and III only c. I only d. I, II, and III e. I and II only

d. I, II, and III

Mixtures that would be considered buffers include which of the following? I. 0.10 M HCl + 0.10 M NaCl II. 0.10 M HF + 0.10 M NaF III. 0.10 M HBr + 0.10 M NaBr a. III only b. II and III c. I only d. II only e. I and II

d. II only

Forms a compound having the formula KXO4 a. S b. F c. Mg d. Mn e. Ar

d. Mn

A precipitation reaction

d. Pb^2+(aq) + CrO4^2-(aq)--->PbCrO4(s)

Which of the following is a graph that describes the pathway of reaction that is endothermic and has high activation energy?

e

The oxidation of iodide ions by arsenic acid in acidic aqueous solution occurs according to the stoichiometry shown above. The experimental rate law of the reaction is: Rate = k [H3AsO4] [I ̄] [H3O+]. What is the order of the reaction with respect to I ̄? a. 3 b. 2 c. 5 d. 6 e. 1

e. 1

The specific rate constant k for radioactive element X is 0.023 min -1. What weight of X was originally present in a sample if 40. grams is left after 60. minutes? a. 20. grams b. 80. grams c. 10. grams d. 120 grams e. 160 grams

e. 160 grams

When the equation for the half-reaction above is balanced, what is the ratio of the coefficients OH ̄ / CrO2 ̄ ? a. 2:1 b. 3:1 c. 1:1 d. 5:1 e. 4:1

e. 4:1

When the equation above is balanced and all coefficients are reduced to lowest whole numbers, the coefficients for H2O(l) is a. 8 b. 4 c. 2 d. 6 e. 5

e. 5

When the equation for the half reaction above is balanced with the lowest whole-number coefficients, the coefficient for H2O is a. 2 b. 6 c. 14 d. 4 e. 7

e. 7

If 25.0 milliliters of 0.200-molar BrO3 ̄ is mixed with 30.0 milliliters of 0.450-molar Br ̄ solution that contains a large excess of H+, the amount of Br2 formed, according to the equation above, is a. 1.62 x 10^ ̄2 mole b. 1.50 x 10^ ̄2 mole c. 1.35 x 10^ ̄2 mole d. 5.00 x 10^ ̄3 mole e. 8.10 x 10^ ̄3 mole

e. 8.10 x 10^ ̄3 mole

Has amphoteric properties a. Aluminum hydroxide b. Hydrofluoric acid c. Hydrogen peroxide d. Carbon dioxide e. Ammonia

e. Ammonia

A precipitation reaction

e. Ca^2+(aq) + SO2^2-(aq) ---> CaSO4(s)

The point at which the pH is closest to that of the strong base being added. a. A b. B c. C d. D e. E

e. E

A buffer at pH<6 a. HCl and NaCl b. NH3 and NH4Cl c. NH3 and HC2H3O2 (acetic acid) d. NaOH and NH3 e. H3PO4 and NaH2PO4

e. H3PO4 and NaH2PO4

Equal numbers of moles of HCl and O2 in a closed system are allowed to reach equilibrium as represented by the equation above. Which of the following must be true at equilibrium? I. [HCl] must be less than [Cl2]. II. [O2] must be greater than [HCl]. III. [Cl2] must equal [H2O]. a. I and III only b. II only c. I only d. I, II, and III e. II and III only

e. II and III only

Which of the following is the conjugate acid of NH2-? a. NH2- b. NH4+ c. H2O d. H+ e. NH3

e. NH3

A buffer at pH>8 a. HCl and NaCl b. H3PO4 and NaH2PO4 c. NH3 and HC2H3O2 (acetic acid) d. NaOH and NH3 e. NH3 and NH4Cl

e. NH3 and NH4Cl

Which of the following ions has the same number of electrons as Br-? a. Cl- b. Ca2+ c. I- d. K+ e. Sr2+

e. Sr2+

Ionization Constants CH3COOH = 1.8 x 10 ̄5 NH3 = 1.8 x 10 ̄5 H2CO3; K1 = 4 x 10 ̄7 H2CO3; K2 = 4 x 10 ̄11 A solution prepared to be initially 0.5 M in CH3COOH and 1 M in CH3COONa a. a solution with a pH of 7 b. a buffer solution with a pH between 7 and 10 c. a solution with a pH greater than 7 that is not a buffer solution d. a solution with a pH less than 7 that is not a buffer solution e. a buffer solution with a pH between 4 and 7

e. a buffer solution with a pH between 4 and

What is the pH of a 1.0x10-2-molar solution of HCN? (For HCN, Ka= 4.0x10-10) a. Between 4 and 7 b. 7 c. 4 d. 10 e. Between 7 and 10

e. a buffer solution with a pH between 4 and

Are the most likely to form anions a. alkali metals b. actinides c. transition elements d. noble gases e. halogens

e. halogens