Physical Chemistry Answers

Question 5 : In the following reaction, which is a Brønsted-Lowry base?
H
C
2
O
−
4
(
a
q
)
+
H
2
O
(
l
)
→
H
3
O
+
(
a
q
)
+
C
2
O
2
−
4
(
a
q
)
HC2O4−(aq)+H2O(l)→H3O+(aq)+C2O42−(aq)


H
3
O
+
H3O+


H
2
O
H2O

None of these

H
C
2
O
−
4
HC2O4−


Question 6 : For the following reaction, which of the following is a conjugate acid-base pair?
H
2
P
O
4
−
(
a
q
)
+
N
H
3
(
a
q
)
→
H
P
O
2
−
4
(
a
q
)
+
N
H
+
4
(
a
q
)
H2PO4−(aq)+NH3(aq)→HPO42−(aq)+NH4+(aq)

None of the above

H
2
P
O
−
4
H2PO4−
and
H
P
O
2
−
4
HPO42−


H
2
P
O
−
4
H2PO4−
and
N
H
3
NH3

HPO42- and NH4+

Question 7 : A Brønsted-Lowry base is defined as a substance that
decreases [H+] when placed in water.
acts as a proton donor.
increases [H+] when placed in water.
acts as a proton acceptor.

Question 1 : Consider the equilibrium of AgCl(s) in water. What is the effect of adding KCl?
The reaction goes to the left
Silver chloride solubility increases
The KCl has no effect
The reaction goes to the right

Question 2 : A Brønsted-Lowry acid is defined as a substance that ______ .
acts as a proton acceptor
decreases [H3O+] when dissolved in water
increases [OH– ] when dissolved in water
acts as a proton donor

Question 3 : The pH of a solution is 4.6; what is its pOH?
9.4
4.6
11.6
2.4

Question 4 : What is the conjugate base of
H
C
O
−
3
HCO3−
?

C
O
2
−
3
CO32−


H
2
C
O
3
H2CO3

OH^{-}

H
C
O
+
3
HCO3+

A mixture of 2.0 x 10^-3 kg of H2 and 2.0 x 10^-3 kg of He exerts a pressure of 1.5 x 10^5 Pa. What are the partial pressures of H2 and He ?

How many atoms do mercury vapour molecules consist of if the density of mercury vapour relative to air is 6.92.The average mass of air is 29g/mol

Question 17 : How many coulombs of charge pass through a cell if 2.40 amperes of current are passed through the cell for 85.0 minutes?
204 C
2120 C
12200 C
0.133 C

Question 18 : Which of the followings is not a Bronsted acid?
HCl

H
2
S
O
4
H2SO4


A
l
C
l
3
AlCl3


H
N
O
3
HNO3


Question 19 : Which of the following mixtures produces a buffer solution?
0.300 M
K
N
O
3
KNO3
+ 0.100 M NaCl (50 mL each)
0.400 M
C
H
3
C
O
O
H
CH3COOH
+ 0.100 M
C
H
3
C
O
O
N
a
CH3COONa
(50 mL each)
0.300 M
N
H
4
C
l
NH4Cl
+ 0.100 M HCl (50 mL each)
0.300 M NaOH + 0.100 M HCl (50 mL each)

Question 20 : The common-ion effect
promotes evaporation.
promotes condensation
reduces ionization.
increases solubility

Question 13 : How long would a constant current of 18.0 amperes be required to flow in order for 9000. coulombs of charge to pass through a cell
50 s
0.002 s
200 s
500 s

Question 14 : The conjugate base of HCl is
HOCl

H
+
H+


O
H
−
OH−


C
l
−
Cl−


Question 15 : Buffering is:
all of these
due to LeChatelier's Principle
influenced by the common ion effect
is a process that is done by a solution made up of a weak acid and its salt

Question 16 : Which of these is incorrect about the pH of a solution?
pH = -log
[
H
+
]
[H+]

an alkali has a higher pH value than an acid
The higher the pH, the more acidic the solution is
It is a measure of the acidity of the solution

Question 10 : What’s the concentration of Ag+ ion in a saturated silver chloride solution?
K
s
p
Ksp
= 1.56 x
10
−
10
10−10
.
none of these
0.000339 M
0.0000125 M
4.90 M

Question 11 : A substance that is capable of acting as both an acid and as a base is _____.
conjugated
Amphoteric
Diprotic
Binary acid-base

Question 12 : The pH of a neutral solution is
6
8
5
7

Question 7 : A Brønsted-Lowry base is defined as a substance that
decreases [H+] when placed in water.
acts as a proton donor.
increases [H+] when placed in water.
acts as a proton acceptor.

Question 8 : The magnitude of
K
w
Kw
indicates that __________.
water autoionizes very quickly
the autoionization of water is exothermic
water autoionizes very slowly
water autoionizes only to a very small extent

Question 9 : For the following reaction, which of the following is a conjugate acid-base pair?
H
C
2
O
−
4
(
a
q
)
HC2O4−(aq)
+
H
2
O
(
l
)
H2O(l)
→
→
H
3
O
+
H3O+
(aq) +
C
2
O
2
−
4
C2O42−
(aq)

H
2
O
H2O
and
C
2
O
4
2
−
C2O42−


H
C
2
O
−
4
HC2O4−
and
H
3
O
+
H3O+


H
C
2
O
−
4
HC2O4−
and
C
2
O
2
−
4
C2O42−


H
C
2
O
−
4
HC2O4−
and
H
2
O
H2O