AP Chem Full Midterm Review (Units 1-6 Questions with Correct Answers
Question 1:
A solution is prepared by adding 16.0 g of CH OH to 90.0 g of H2O. The mole fraction of CH OH
in this solution is closest to which of the following?
a, 0.1
b. 0.2
c. 0.3
d 0.4
Answer:
b. 0.2
In 1.00 mol of potassium zirconium sulfate trihydrate, KaZr(SO4)4 • 3 H2O, there are a 1.81 x
1024 hydrogen atoms
6.02 × 1023 sulfur atoms
2.41 x 1024 potassium atoms 4 moles of oxygen atoms
Question 2:
4 moles of zirconium atoms
Answer:
c. 2.41 x 1024 potassium atoms
Question 3:
A student has a 1.0 g sample of each of the following compounds: NaCI, KBr, and KCL Which of
the following lists the samples in order of increasing number of moles in the sample?
NaCI < KCI < KBr NaCI < KBr < KCI KCI < NaCI < KBr KBr < KCI < NaCI
Answer:
a. NaCI < KCI < KBr
Question 4:
A student obtains a sample of a pure solid compound. In addition to Avogadro's number, which
of the following must the student know in order to determine how many molecules are in the
sample?
Mass of the sample, volume of the sample Mass of the sample, density of the sample
Molar mass of the compound, mass of the sample Molar mass of the compound, density of the
sample
Answer:
C. Molar mass of the compound, mass of the sample
,Question 5:
According to the information in the table at right, a 1.00 g sample of which of the following
contains the greatest mass of oxygen?Na.OMgO K20CaO
Answer:
b. MgO
Question 6:
According to the information in the table at right, a 1.00 g sample of which of the following
contains the greatest mass of oxygen?
Na.O
MgO K20
CaO
Answer:
b. MgO
Question 7:
What differentiates a homogeneous mixture from a pure substance? The composition of a pure
substance is fixedA pure substance can be separated into elements by physical meansA pure
substance is always a compound while mixtures can be elements or compounds A
homogeneous mixture is uniform throughout
Answer:
a. The composition of a pure substance is fixed
Question 8:
What differentiates a homogeneous mixture from a pure substance? The composition of a pure
substance is fixed
A pure substance can be separated into elements by physical means
A pure substance is always a compound while mixtures can be elements or compounds A
homogeneous mixture is uniform throughout
Answer:
a. The composition of a pure substance is fixed
,Question 9:
A student is given two 10 g samples, each a mixture of only NaC(sand Cs) but in different
proportions. Which of the following pieces of information could be used to determine which
mixture has the higher proportion of KCI(s)?
The volume o each mixure The mass of Cl in each mixture
The number of isotopes of Na and K
The reaction or each mixture with water
Answer:
b. The mass of Cl in each mixture
An experiment is performed to measure the mass percent of CaCOs(s) in eggshells. Five
different samples of CaCOss) of known mass react with an excess of 2.0 M HClag) in identical
sealed, rigid reaction vessels.
The
pressure of he gas proouceds measured win a pressure gauge atached o me reaction vessel,
since me reactions exoteric me reaction system is cooleo to ns onginartemperature before te
pressure is recorded The experimental dala are used to creale tre Caloraton Iine befou 5 Ca Coz
+ 2.0M HCkag)
The experiment is repeated with an eggshell sample, and the experimental data are recorded in
the table below.
The mass percent of CaCOss) in the eggshell sample is closest to 30%
45%
60%
Question 10:
75%
Answer:
d. 75%
Question 11:
The percentage of silver in a solid sample is determined gravimetrically by converting the silver
to Ag aq) and precipitating it as silver chlonde. Failure to do which of the following could cause
errors in the analysis?
I Account for the mass of the weighing paper when the mass of the sample Measure the
temperaure during the preciptation reaction
wash me precipitate
Heat the AgCI precipitate to constant mass I only
I and Il I and IV I and III
I, III and IV
Answer:
e. I, III and IV
, Question 12:
A 5.0 g sample of MgCl2 may contain measurable amounts of other compounds as impurities.
Which of the following quantities is (are) needed to determine that the sample is pure MgCI2?
The color and density of the sample The mass of Mg in the sample only
The number of moles of Cl in the sample only The mass of Mg and the mass or clin the sample
Answer:
d. The mass of Mg and the mass of Cl the sample
Question 13:
To gravimetrically analyze the silver content of a piece of jewelry made from an alloy of Ag and
Cu, a student dissolves a small pre-weighed sample in HNO3(ag). Ag*(ag) and Cu?*(ag) ions
form in the solution. Which of the following should be the next step in the analytical process?
Centrifuging the solution to isolate the heavier ions Evaporating the solution to recover the
dissolved nitrates Adding enough base solution to bring the pH up to 7.0
Adding a solution containing an anion that forms an insoluble salt with only one of the metal
ions
Answer:
d. Adding a solution containing an anion that forms an insoluble salt with only one of the metal
ions
Question 14:
The mass percent of carbon in pure glucose, C6H1206, is 40.0 %. A chemist analyzes an impure
sample of glucose and determines that the mass percent of carbon is 38.2%. Which of the
following impurities could account for the low mass percent of carbon in the sample?Water,
H20Fructose, C6H1206, isomer of glucose Ribose, C5H1005Sucrose, C12H22011
Answer:
a. Water, H20
Question 15:
sample of a solid labeled as NaCI may be impure. A student analyzes the sample and
determines that it contains 75 percent chlorine by mass. Pure NaCI(s) contains 61 percent
chlorine by mass. Which of the following statements is consistent with the data?
The sample contains only NaCI(s)
The sample contains NaCI(s) and Nals) The sample contains NaCI(s) and KCI(s) The sample
contains NaCI(s) and LiCI(s)
Answer:
d. The sample contains NaCI(s) and LiCI(s)
The atom that contains exactly two unpaired electrons S
Ca Ga Sb
Question 1:
A solution is prepared by adding 16.0 g of CH OH to 90.0 g of H2O. The mole fraction of CH OH
in this solution is closest to which of the following?
a, 0.1
b. 0.2
c. 0.3
d 0.4
Answer:
b. 0.2
In 1.00 mol of potassium zirconium sulfate trihydrate, KaZr(SO4)4 • 3 H2O, there are a 1.81 x
1024 hydrogen atoms
6.02 × 1023 sulfur atoms
2.41 x 1024 potassium atoms 4 moles of oxygen atoms
Question 2:
4 moles of zirconium atoms
Answer:
c. 2.41 x 1024 potassium atoms
Question 3:
A student has a 1.0 g sample of each of the following compounds: NaCI, KBr, and KCL Which of
the following lists the samples in order of increasing number of moles in the sample?
NaCI < KCI < KBr NaCI < KBr < KCI KCI < NaCI < KBr KBr < KCI < NaCI
Answer:
a. NaCI < KCI < KBr
Question 4:
A student obtains a sample of a pure solid compound. In addition to Avogadro's number, which
of the following must the student know in order to determine how many molecules are in the
sample?
Mass of the sample, volume of the sample Mass of the sample, density of the sample
Molar mass of the compound, mass of the sample Molar mass of the compound, density of the
sample
Answer:
C. Molar mass of the compound, mass of the sample
,Question 5:
According to the information in the table at right, a 1.00 g sample of which of the following
contains the greatest mass of oxygen?Na.OMgO K20CaO
Answer:
b. MgO
Question 6:
According to the information in the table at right, a 1.00 g sample of which of the following
contains the greatest mass of oxygen?
Na.O
MgO K20
CaO
Answer:
b. MgO
Question 7:
What differentiates a homogeneous mixture from a pure substance? The composition of a pure
substance is fixedA pure substance can be separated into elements by physical meansA pure
substance is always a compound while mixtures can be elements or compounds A
homogeneous mixture is uniform throughout
Answer:
a. The composition of a pure substance is fixed
Question 8:
What differentiates a homogeneous mixture from a pure substance? The composition of a pure
substance is fixed
A pure substance can be separated into elements by physical means
A pure substance is always a compound while mixtures can be elements or compounds A
homogeneous mixture is uniform throughout
Answer:
a. The composition of a pure substance is fixed
,Question 9:
A student is given two 10 g samples, each a mixture of only NaC(sand Cs) but in different
proportions. Which of the following pieces of information could be used to determine which
mixture has the higher proportion of KCI(s)?
The volume o each mixure The mass of Cl in each mixture
The number of isotopes of Na and K
The reaction or each mixture with water
Answer:
b. The mass of Cl in each mixture
An experiment is performed to measure the mass percent of CaCOs(s) in eggshells. Five
different samples of CaCOss) of known mass react with an excess of 2.0 M HClag) in identical
sealed, rigid reaction vessels.
The
pressure of he gas proouceds measured win a pressure gauge atached o me reaction vessel,
since me reactions exoteric me reaction system is cooleo to ns onginartemperature before te
pressure is recorded The experimental dala are used to creale tre Caloraton Iine befou 5 Ca Coz
+ 2.0M HCkag)
The experiment is repeated with an eggshell sample, and the experimental data are recorded in
the table below.
The mass percent of CaCOss) in the eggshell sample is closest to 30%
45%
60%
Question 10:
75%
Answer:
d. 75%
Question 11:
The percentage of silver in a solid sample is determined gravimetrically by converting the silver
to Ag aq) and precipitating it as silver chlonde. Failure to do which of the following could cause
errors in the analysis?
I Account for the mass of the weighing paper when the mass of the sample Measure the
temperaure during the preciptation reaction
wash me precipitate
Heat the AgCI precipitate to constant mass I only
I and Il I and IV I and III
I, III and IV
Answer:
e. I, III and IV
, Question 12:
A 5.0 g sample of MgCl2 may contain measurable amounts of other compounds as impurities.
Which of the following quantities is (are) needed to determine that the sample is pure MgCI2?
The color and density of the sample The mass of Mg in the sample only
The number of moles of Cl in the sample only The mass of Mg and the mass or clin the sample
Answer:
d. The mass of Mg and the mass of Cl the sample
Question 13:
To gravimetrically analyze the silver content of a piece of jewelry made from an alloy of Ag and
Cu, a student dissolves a small pre-weighed sample in HNO3(ag). Ag*(ag) and Cu?*(ag) ions
form in the solution. Which of the following should be the next step in the analytical process?
Centrifuging the solution to isolate the heavier ions Evaporating the solution to recover the
dissolved nitrates Adding enough base solution to bring the pH up to 7.0
Adding a solution containing an anion that forms an insoluble salt with only one of the metal
ions
Answer:
d. Adding a solution containing an anion that forms an insoluble salt with only one of the metal
ions
Question 14:
The mass percent of carbon in pure glucose, C6H1206, is 40.0 %. A chemist analyzes an impure
sample of glucose and determines that the mass percent of carbon is 38.2%. Which of the
following impurities could account for the low mass percent of carbon in the sample?Water,
H20Fructose, C6H1206, isomer of glucose Ribose, C5H1005Sucrose, C12H22011
Answer:
a. Water, H20
Question 15:
sample of a solid labeled as NaCI may be impure. A student analyzes the sample and
determines that it contains 75 percent chlorine by mass. Pure NaCI(s) contains 61 percent
chlorine by mass. Which of the following statements is consistent with the data?
The sample contains only NaCI(s)
The sample contains NaCI(s) and Nals) The sample contains NaCI(s) and KCI(s) The sample
contains NaCI(s) and LiCI(s)
Answer:
d. The sample contains NaCI(s) and LiCI(s)
The atom that contains exactly two unpaired electrons S
Ca Ga Sb
