AP Chem Exam

The point at which the pH is closest to that of the strong base being added

D

which of the following best helps to account for the fact that the F- ion is smaller than the O2- ion

F- has a larger nuclear charge than O2- has

the london dispersion forces are weakest for which of the following gases under the same conditions of temperature and pressure

H2

must be true for a reaction that is spontaneous at all temperatures

H<0, S>0

true for the combustion of liquid pentane, C5H12 to form H2O and C)2 at 1 atm

H<0, S>0

true for the evaporation of water at 25C and 1 atm

H>0, S>0

Is a strong electrolyte in aqueous solution

HBr

Is the slowest to effuse through a small opening at 25C and 1 atm

HBr

a 360mg sample of aspirin, C9H8O4 (molar mass 180g), is dissolved in enough water to produce 200mL of solution. what is the molarity of aspirin in a 50mL sample of this solution

.0100 M

which of the following solutions has a pH greater than 7

.10 M NaF

if .40mol of H2 and .15mol of O2 were to react as completely as possible to produce H2O what mass of reactant would remain

.20 g of H2

a solution is prepared by adding 16g of CH3OH (molar mass 32 g) to 90g of H2O (molar mass 18g). the mole fraction of CH3OH is closest to which of the following

0.1

the nonvolatile compound ethylene glycol, C2H6O2, forms nearly ideal solutions with water. what is the vapor pressure of the solution made from 1 mol of C2H6O2 and 9mols of H2O if the vapor pressure of pure water at the same temperature is 25 mmHg

22.5 mmHg

which of the following is a correctly balanced nuclear reaction

238 92U + 1 0N --> 239 92U

which of the following pieces of laboratory glassware should be used to most accurately measure out a 25mL sample of a solution

25 mL pipet

on the basis of this information to how many significant figures should the density of the liquid be reported

4

when is balanced and all coefficients are reduced to lowest whole-numbers the coefficient for H3PO4 is

4

when the equation is balanced and all coefficients are reduced to lowest whole-numbers the coefficient for H2) is

4

The point at which the concentrations of the weak acid and its conjugate base are approximately equal

B

which of the following ions has the same number of electrons as Br

Sr2+

salts containing which of the following ions are generally insoluble in cold water

phosphate

what is the hybridization of the carbon atoms in ethyne

sp

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

t4

the vapor pressure of the acetone is

the same in both containers bc the temperature is the same

when diluting concentrated H2SO4 one should slowly add acid to a beaker of water rather than add water to a beaker of acid. the reason for this precaution is to ensure that

there is a sufficient volume of water to absorb the heat released

a pure liquid in an open vessel boils at the temperature at which the

vapor pressure of the liquid becomes equal to the atmospheric pressure on the surface of the liquid

Has molecules with a pyramidal shape

NH3

which of the following is the conjugate acid of NH2-

NH3

when mixed each of the following pairs of reactants gives visible evidence of a chemical reaction except

NH4Cl + HCL

when the aqueous NH3 is first added to a solution containing Ni2+ a precipitate forms but when an excess of aqueous NH3 is added the precipitate dissolves. which of the following best explains why the precipitate dissolves

Ni2+ forms a complex ion with NH3

of the following single bonds which is the least polar

O-F

which of the following molecules has an angular (bent) geometry that is commonly represented as a resonance hybrid of two or more electron-dot structures

O3

a precipitation reaction

Pb2 + CrO42- --> PbCrO4

a compound contains 30 percent sulfur and 70 percent flourine by mass. the empirical formula of the compound is

SF4

which of the following elements combines with oxygen to form a covalent network solid

Si

the pressure in atm exerted by 1.85 mol of an ideal gas placed in a 3 L container at 35C is given by which of the following expressions

(1.85)(0.0821)(308)/3atm

according to the equation above, how many moles of potassium chlorate, KClO3, must be decomposed to generate 1 L of O2 gas at STP

2/3 (1/22.4) mols

are the most likely to form anions

halogens

the oxidation state that is common to aqueous ions of Fe, Mn, and Zn is

+2

the diagram above represents a mixture of NO2 and N2O4 in a 1L container at a given temperature. the two gases are in equilibrium according to the equation 2 NO2 and N2O4. which of the following must be true about the value of the equilibrium constant for the reaction at this temperature

0<K<1

how many carbon atoms are contained in 2.8 g of C2H4

1.2 x 10 23

how many electrons are transferred in the reaction represented by the balanced equation above?

10

how many mL of 10M HCl are needed to prepare 500mL of 2M HCl

100mL

the pH of a solution prepared by the addition of 10mL of .002M KOH to 10mL of distilled water is closest to

11

an electric current of 1 ampere is passed through an aqueous solution of Ni(No3)2. how long will it take to plate out exactly 1 mol of nickel metal assuming 100 percent current efficiency

193,000 s

of the following electron configurations of neutral atoms, which represents an atom in an excited state

1s2 2s2 2p5 3s2

an oxidation-reduction that is also a synthesis reaction

2 Mg + O2 --> 2 MgO

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

2R

the reaction mixture represented above is at equilibrium at 298K and the molar concentrations are X = 2M, Y = .5M, and Z = 4M. what is the value of the equilibrium constant for the reaction at 298K.

32

gaseous cyclobutene undergoes a first-order reaction to form gaseous butadiene. at a particular temperature, the partial pressure of cyclobutene in the reaction vessel drops to one-eighth its original value in 120 seconds. what is the half-life for this reaction at this temperature

40s

equal masses of He and Ne are placed in a sealed container. what is the partial pressure of He if the total pressure in the container is 6 atm

5 atm

which of the following shows the correct number of protons, neutrons, and electrons in a neutral cesium-134 atom

55, 79,55

under which of the following conditions of temperature and pressure would 1.0mol of the real gas CO2 behave most like an ideal gas

800K and 0.1 atm

on the basis of strength of intermolecular forces which of the following elements would be expected to have the highest melting point

Br2

The point at which the moles of the added strong base are equal to the moles of the weak acid initially present

C

which of the following diagrams would represent the results if the reaction were to proceed as far as possible

C

which of the following molecules contains only single bonds

C2H6

which of the following is a nonpolar molecule that contains polar bonds

CO2

which of the following best accounts for the fact that a galvanic cell based on the reaction represented above will generate electricity

Cl2 is a stronger oxidizing agent that I2

a student mixes equal volumes of 1M tin(ll) sulfate and observes that no precipitate forms. then the student mixes equal volumes of 1M zinc(ll) sulfate and tin(ll) flouride and observes the formation of a precipitate. the formula of the precipitate must be

ZnF2

are always radioactive

actinides

quantity typically determined by measuring the rate of a reaction at two or more different temperatures

activation energy

naturally produced amino acids typically contain all of the following elements except

chlorine

quantity that would be zero for a pure, perfect crystal at 0 K

entropy

at STP a .50mol H2 gas and 1 mol O2 gas have the same

kinetic energy

which of the following changes to the equilibrium system will increase the quantity of HI in the mixture

l and ll only

factors that affect the rate of a chemical reaction include which of the following

l, ll, and lll

in solid methane, the forces btn neighboring CH4 molecules are best characterized by

london dispersion forces

a sample of 10 mol of butyric acid, HC4H7O2, a weak acid, is dissolved in 1000g of water to make a 10 molal solution. which of the following would be the best method to determine the molarity of the solution?

measurement of the total volume of the solution

which of the following measures of concentration changes with temperature

molarity

the temperature of the water is 21C and the atmospheric pressure in the laboratory is measured to be 772 torr. before measuring the volume of gas collected in the tube, what step, if any, must be taken to make it possible to determine the total gas pressure inside the tube

move the tube downward until the water level is the same inside and outside the tube

are the most difficult to oxidize in a given period of the periodic table

noble gases