Final Exam AP Chemistry

Final Exam AP Chemistry

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Section 1

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Consider the following reaction at equilibrium 2NH3 (g) -> N2 (g) + 3H2 (g) delta H = +92.5 kJ Le Chatelier's principle predicts that adding N2 (g) to the system at equilibrium will result in _____

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Cards (93)

Section 1

(50 cards)

Consider the following reaction at equilibrium 2NH3 (g) -> N2 (g) + 3H2 (g) delta H = +92.5 kJ Le Chatelier's principle predicts that adding N2 (g) to the system at equilibrium will result in _____

Front

a decrease in the concentration of H2??

Back

The equilibrium constant for reaction 1 is K. The equilibrium constant for reaction 2 is ____ 1) SO2 (g) + 1/2 O2 (g) -> SO3 (g) 2) 2SO3 (g) -> 2SO2 (g) + O2 (g)

Front

1/K^2

Back

What is the coefficient of the permanganate ion when the following equation is balanced? MNO4- +Br- -> Mn2+ +Br2 (acidic solution)

Front

2

Back

The decomposition of n2O5 rate law is

Front

K[N2O5]

Back

The equilibrium constant for the reaction shown here is Kc = 1.0x10^3. A reaction mixture at equilibrium contains [A] = 1.0 x 10^-3 M. What is the concentration of B in the mixture A(g) -> B(g)

Front

1.0M

Back

NO3 + CO -> NO2 + CO2 Molecularity is_____ rate law is _____

Front

2, k[NO3][CO]

Back

Which Substance in the reaction below either appears or disappears the fastest? 4NH3 + 7O2 -> 4NO2 + 6H2O

Front

O2

Back

Which energy difference corresponds to the activation energy if the reverse reaction

Front

X + y

Back

What is the oxidation number of manganese in the MnO4- ion?

Front

7+

Back

The balanced half-reaction in which sulfate ion is reduced to sulfite ion is a

Front

two electron process

Back

The expression for Keq for the reaction below is BaS (s) + 2O2 (g) -> BaSO4 (s)

Front

1/P O2^2

Back

one difference between first and second-order reactions is that

Front

the half-life of a first-order reaction does not depend on [A]0; the half-life of a second-order reaction does depend on [A]0

Back

A reaction was found to be third order in A. Increasing the concentration of A by a factor of 3 will cause the reaction rate to

Front

increase by a factor of 27

Back

Which transformation could take place at the cathode of an electrochemical cell

Front

HSO4- -> H2SO3

Back

A burning splint will burn more vigorously in pure oxygen than in air because

Front

oxygen is a reactant in combustion and concentration of oxygen is higher in pure oxygen than in air

Back

Nitrogen dioxide decomposes to nitric oxide and oxygen via the reaction.... in a particular experiment at 300C, NO2 drops from .01 to .0065 M in 100 s. The rate of appearance of O2 for this period is

Front

7x10^-5

Back

2NH3 g -> N2 g + 3H2 g Is keq = 230 at 300C at equilibrium

Front

Products are predominant

Back

The solid XY decomposes into gaseous X and Y XY (s) -> X (g) + Y (g) Kp = 4.1 at 0C If the reaction is carried out in a 22.4L container, which initial amount of X and Y will result in the formation of solid XY?

Front

Back

Consider the following reaction at equili rium: 2CO2 (g) -> @CO (g) +O2 (g) delta H = -514 kJ Le Chatelier's principle predicts that an increase in temperature will ____

Front

decrease the value of the equilibrium constant

Back

Nuclear decay is ____ order and half lives ___

Front

First, remains constant

Back

Under constant conditions, the half-life of a fist-order reaction

Front

does not depend on the initial reactant concentration, is constant, can be calculated from the reaction rate constant, is the time necessary for the reactant concentration to drop to half its original value (aka all of the above)

Back

Which of the following expression is the correct equilibrium-constant expression for the equilibrium between dinitrogen tetroxide and nitrogen dioxide? N2O4 (g) -> 2NO2 (g)

Front

[NO2]2 / N2O4

Back

Which element is reduced in the reaction below? Fe(CO)5 (l) + 2HI (g) -> Fe(CO)4I2 (s) + CO (g) + H2 (g)

Front

H

Back

Which of the following reactions initially at equilibrium will form more products when the pressure is increased as constant temperature

Front

N2 (g) + 3H2 (g) -> 2NH3 (g)

Back

Of the following, all are valid units for a reaction rate except

Front

mole/L

Back

Which one of the following will change the value of an equilibrium constant?

Front

changing temperature

Back

If the rate law for the reaction 2A +3B -> products is first order in A and second order in B then the rate law is rate =

Front

k[A][B]^2

Back

The rate law of the reaction A + B -> C and positive delta h is k[A]2 which will not increase rate

Front

Increasing the concentration of reactant b

Back

At equilibrium

Front

The rates of the forward and reverse reactions are equal

Back

At 400K the equilibrium constant for the reaction Br2 (g) + Cl2 (g) -> 2BrCl (g) is Kp = 7.0. A closed vessel at 400k is charged with 1.00 atm of Br2 (g), 1.00 atm of Cl2 (g) and 2.00 atm of BrCl (g). Use Q to determine which of the statements below is true

Front

The equilibrium partial pressure of BrCl (g) will be greater than 2.00 atm

Back

Consider the general reaction A + B -> C + D with a Keq = 3.2 If the reaction is allowed to reach equilibrium, what is the value of delta g?

Front

delta g will be less than 1

Back

which of the following reactions is a redox reaction?

Front

CU + S -> CuS

Back

for the endothermic reaction CaCO3 (s) -> CaO (s) + CO2 (g) le chatelier's principle predicts that _____ will result in an increase in the number of moles of CO2

Front

increasing the temperature

Back

The purpose of the salt bridge in an electrochemical cell is to _____

Front

maintain electrical neutrality in the half-cells via migration of ions

Back

For the reaction 2A(g) -> B(g) the equilibrium constant is Kp = 0.76. A reaction mixture initially contains 2.0 atm of each gas. Which statement is true of the reaction mixture?

Front

the reaction mixture will proceed towards products

Back

how does the reaction quotient of a reaction (Q) compare with the equilibrium constant (Keq) of the same reaction

Front

Q is the same as Keq when the reaction is at equilibrium

Back

Which is an intermediate in the formation of XO2 from X and O2

Front

XO

Back

Consider the following equilibrium 2SO2 (g) + O2 (g) -> 2SO3 (g) - the equilibrium cannot be established when ____ is/are placed in a 1.0L container

Front

.75 mol SO2 (g)

Back

Which one of the following graphs shows the correct relationship between concentration and time for a reaction that is second order in [A]?

Front

x axis = time, y axis = 1/[A]

Back

the electrode at which an oxidation occurs is called the

Front

anode

Back

In general, as activation energy increases, reaction rate

Front

Goes down regardless of whether the reaction is exothermic or endothermic

Back

the gain of electrons by an element is called

Front

reduction

Back

Nitrosyl bromide decomposes according to the following equation 2NOBr (g) -> 2NO (g) + Br2 (g) 2NOBr (0.64 mol) was placed in a 1.00 L flask containing no NO or Br2. At equilibrium the flask contained 0.46 mol of NOBr. How many moles of NO and Br2 respectively, are in the flask at equilibrium?

Front

0.18, 0.090

Back

The decomposition of NH4HS is endothermic: NH4Hs (s) -> NH3(g) + H2S (g) which change to an equilibrium mixture of this reaction results in the formation of more H2S?

Front

An increase in temperature

Back

The overall order of a reaction is 2. The units of the rate constant for the reaction are

Front

M-1s-1

Back

For which of the following reactions is the value of Kp equal to Kc?

Front

SnO2 (s) + 2H2 (g) + Sn(s) + 2H2O (g)

Back

The graph shown below depicts the relationship between concentration and time for the following chemical reaction 2A -> C The slope of the line is equal to

Front

-k

Back

A catalyst can increase the rate of reaction

Front

By providing an alternative pathway with a Lowe activation energy

Back

The rate law for this reaction (A + B -> P) =

Front

k[A]^2

Back

The more ___ the value of the E^0 red, the greater the driving force for reduction

Front

positive

Back

Section 2

(43 cards)

Which of the halogens in table 20.1 is the strongest oxidizing agent (will be reduced)?

Front

F2

Back

Of the following, delta H of formation is not zero for

Front

F2 (s)

Back

The combustion of acetylene in the presence of excess oxygen yields carbon dioxide and water 2C2H2 (g) + 5O2 (g) -> 4CO2 (g) + 2H2O (l) The value of delta s for this reaction is _____ J/K

Front

-432.4

Back

The reaction 4Al (s) + 3O2 (g) -> 2Al2O3 (s) delta H = -3351 kJ is ____ and there heat is ____ by the reaction

Front

exothermic, released

Back

One of the differences between a voltaic cell and an electrolytic cell is that in an electrolytic cell, _______

Front

a non-spontaneous reaction is forced to occur

Back

Given the reaction 2C (s, diamond) + O2 (g) -> 2CO (g) which of the following statements is true?

Front

diamonds only react with air at very high temperatures to produce CO

Back

Consider the following two reactions: A -> 2B delta H rxn = 456.7 kJ/mol A -> C delta H rxn = -22.1 kJ/mol Determine the enthalpy change for the process: 2B -> C

Front

-478.8 kJ/mol

Back

What change will be caused by addition of a small amount of HCl to a solution containing fluoride ions and hydrogen fluoride

Front

the concentration of fluoride ion will decrease and the concentration of hydrogen fluoride will increase

Back

A solution is prepared by dissolving 0.23 mol of chloroacetic acid and 0.27 mol of sodium chloroacetate in water sufficient to yield 1.00L of solution. The addition of 0.05 mol of HCl to this buffer solution causes the pH to drop slightly. The pH does not decrease drastically because the HCl ______. The Ka of chloroacetic acid is 1.4 x 10^-3

Front

reacts with the chloroacetate present in the buffer soltuion

Back

A 25.0 mL sample of a solution of an unknown compound is titrated with a 0.115 M NaOH solution. The titration curve above was obtained. The half-equivalence point is at

Front

12.5 mL

Back

Which of the compounds I) PCl5 (g) II) NO (g) III) SO2 (g) IV) HCN (g) is/are unstable and will decompose into their elements at 25C?

Front

II and IV only (NO and HCN)

Back

In an electrolytic cell, the direction of the electrons is ______

Front

Back

Under what condition(s) is the enthalpy change of a process equal to the amount of heat transferred into or out of the system a) temperature is constant b) pressure is constant c) volume is constant

Front

pressure

Back

The units of specific heat are ____

Front

J/g-K or J/g-C

Back

In which of the following aqueous solutions would you expect AgCl to have the lowest solubility?

Front

0.020 M BaCl2

Back

The value of delta H for the reaction below is 44kJ H2O (l) -> H2O (g) The value of delta H formation of H2O (g) is ____kJ/mol

Front

+44

Back

The standard cell potential for the voltaic cell based on the reaction below is _____V. Fe (s) + 2Fe^3+ (aq) -> 3Fe^2+ (aq)

Front

+1.21

Back

Two solids, A and B, or equal mass but different specific heat capacity are dropped in boiling water (100C) and the temperature allowed to equilibrate. The solids are then taken out of the water and allowed to reach room temperature (25C). Which solid will release the most heat?

Front

The solid with the higher heat capacity

Back

For which one of the following equations is delta h rxn = delta h f of product?

Front

Xe (g) + 2F2 (g) -> XeF4 (g)

Back

The value of delta H rxn for the reaction below is -186 kJ H2 (g) + Cl2 (g) -> 2HCl (g) The value of delta H f for HCl is _____kJ/mol

Front

-93.0

Back

A ____ delta H corresponds to an _____ process

Front

negative, exothermic

Back

Which of the following is a statement of Hess's law?

Front

If a reaction is carried out in a series of steps the delta H for the reaction will equal the sum of the enthalpy changes for the individual steps

Back

The molar solubility _____ is not affected by the pH of the solution.

Front

KNO3

Back

Which one of the following is is endothermic

Front

boiling soup and ice melting

Back

The addition of hydrofluoric acid and _____ to water produces a buffer solution

Front

NaF

Back

In which one of the following solutions is silver chloride the most soluble?

Front

0.0176 M NH3

Back

The standard cell potential (E^0 cell) for the reaction below is +0.63 V. IF [Zn2+] =1.0M and [Pb2+] = 2.0 x 10^-4 M the cell potential for this reation _____ Pb2+ (aq) + Zn (s) -> Zn 2+ (aq) + Pb (s)

Front

will decrease

Back

To determine the molar mass of a solid monoprotic acid, a student titrated a weighed sample of the acid with standardized aqueous NaOH. Which of the following could explain why the student obtained a molar mass that was too large.

Front

failure to rinse all the acid from the weighing paper into the titration vessel

Back

Consider an electrochemical cell based on the reaction: 2H+ (aq) + Sn (s) -> Sn2+ (aq) + H2 (g) Which of the following actions would change the measured cell potential

Front

any of the above (increasing pressure of hydrogen gas in cathode, increasing pH in cathode, lowering pH in cathode, increasing the [Sn2+] in the anode)

Back

Which insoluble compound should be more soluble in nitric acid than in pure water?

Front

Ag2Co3 and AgCl

Back

Which substance can oxidize I- (aq) to I2 (s)

Front

Br2 (l)

Back

Cathodic protection of a metal pipe against corrosion usually entails

Front

attaching an active metal to make the pope the cathode in an electrochemical cell

Back

Of the following solutions, which has the greatest buffering capacity?

Front

0.400 M HAc and 0.350 M NaAc

Back

Which range includes the pH that results when .1 moles of NaOH is added to 100 ml of 1.0 M HCl solution

Front

between 6.5 and 7.5

Back

Galvanized iron is coated with

Front

zinc

Back

Consider two solids, A and B, of different composition. Compound A has a significantly higher specific heat capacity value than compound B. Both solids are at the same temperature and have the same mass. The solids are then put in contact with each other. Which of the following statements is true?

Front

There is no heat exchange because both solids are at the same temperature

Back

Consider the reaction Ag+ (aq) + Cl- (aq) -> AgCl (s) Given the following table of thermodynamic data, determine the temperature in C above which the reaction is non-spontaneous under standard conditions

Front

1641

Back

A solution of HF is titrated with a 0.150 M NaOH solution. Based on the table above, the best indicator for this reaction is ______. The pka of hydrofluoric acid is 3.16.

Front

methyl red

Back

For which one of the following reactions is delta H rxn equal to the heat of formation of the product?

Front

1/2N2 (g) + O2 (g) -> NO2 (g)

Back

The Ka of acetic acid is 1.7 x 10^-5. The pH of a buffer prepared by combining 50.0 mL of 1.00 M potassium acetate and 50.0 mL of 1.00 M acetic acid is

Front

4.77

Back

KCl is added to a solution that contains equivalent amounts of the following three ions. In what order will the ions precipitate out of solution? PbCl2, Ksp = 1.7 x 10^-5 XCl, Ksp = 1.2 x 10^-18 AgCl, Ksp = 1.8 x 10-10

Front

X+ , Ag+, Pb2+

Back

Which of the following reactions will occur spontaneously as written? (+E red)

Front

Back

In a voltaic cell, electrons flow from the _____ to the ____

Front

anode, cathode

Back