Thursday, Feb. 10
SEC 4
FORMATIVE
QUIZ 7
Name: SOLUTION KEY
Mega Quiz!
100
100
1. Combine the following atoms to form compounds, state whether they’re ionic or
covalent, acid, base, salt or nothing and give the name of the compound that
forms. 24 pts.
Atoms
Compound formed
Ionic or
covalent
Acid, base, salt or
nothing
Name
a. Ca and P
Ca3P2
Ionic
Salt
Calcium Phosphide
b. Li and C
Li4C
Ionic
Salt
Lithium Crabide
c.
P2O3
Covalent
Nothing
Diphosphourous
trioxide
d. N and I
NI3
Covalent
Nothing
Nitrogen triidiode
e. Li and S
Li2S
Ionic
Salt
Lithium sulphide
f.
CaO
Ionic
Salt
Calcium oxide
g. N and O
N2O3
Covalent
Nothing
Dinitrogen trioxide
h. C and F
CF4
Covalent
Nothing
Carbon
tetrafluoride
P and O
Ca and O
2. Combine the following. 60 pts.
Atoms and radicals
a. sodium
b. Magnesium
c.
Ammonium
NH4+1
d. Aluminium
nitrate
NO3-1
sulfate
SO4-2
Carbonate
CO3-2
Phosphate
PO4-3
Hydroxide
OH-1
Chromate
CrO4-2
NaNO3
Na2SO4
Na2CO3
Na3PO4
NaOH
Na2CrO4
Mg(NO3)2
MgSO4
MgCO3
Mg3(PO4)2
Mg(OH)2
MgCrO4
NH4NO3
(NH4)2SO4
(NH4)2CO3
(NH4)3PO4
NH4OH
(NH4)2CrO4
Al(NO3)3
Al2(SO4)3
Al2(CO3)3
AlPO4
Al(OH)3
Al2(CrO4)3
1
nitrate
NO3-1
sulfate
SO4-2
Carbonate
CO3-2
Phosphate
PO4-3
Hydroxide
OH-1
Chromate
CrO4-2
e. Boron
B(NO3)3
B2(SO4)3
B2(CO3)3
BPO4
B(OH)3
B2(CrO4)3
f.
Si(NO3)4
Si(SO4)2
Si(CO3)2
Si3(PO4)4
Si(OH)4
Si(CrO4)2
g. Cu+2
Cu(NO3)2
CuSO4
CuCO3
Cu3(PO4)2
Cu(OH)2
CuCrO4
h. Lead+3
Pb(NO3)3
Pb2(SO4)3
Pb2(CO3)3
PbPO4
Pb(OH)3
Pb2(CrO4)3
KNO3
K2SO4
K2CO3
K3PO4
KOH
K2CrO4
Ca(NO3)2
CaSO4
CaCO3
Ca3(PO4)2
Ca(OH)2
CaCrO4
Atoms and radicals
Silicon
i.
Potassium
j.
Calcium
3. Which substance has only covalent bonding? Circle the correct answer. 1 pt.
a) KCl
c) SO2
b) MgO
d) Na2O
Answer: c
4. Which substance has only ionic bonding? Circle the correct answer. 1 pt.
a) H2O
c)P4O10
b) Na2O
d)CO2
Answer: b
5. Which of the following is a polyatomic ion? Circle the correct answer. 1 pt.
a) H+
c) H2O
Answer: b
b) OH-
d) CO2
2
6. Which is the correct formula for the compound formed by the Al+³ and SO4-2 ions? Circle the
correct answer. 1 pt.
a) AlSO4
c) Al2(SO4)3
b) Al3(SO4)2
d) Al(SO4)3
Answer: c
7. What would be the correct formula for ammonium (NH4+1) and a phosphate ion (PO4-3)? Circle the
correct answer. 1 pt.
a) NH4PO4
c) (NH4)3PO4
Answer: c
b) NH4(PO4)3
d) PO4(NH4)3
8. The formula for aluminum oxalate is Al2(C2O4)3. What is the charge of the oxalate ion,C2O4 ? Circle
the correct answer. 1 pt.
a) -1
c) -6
b) -3
d) -2
Answer: d
9. Calculate the molecular molar mass for the following: 4 pts.
Al2(SO4)3
342
CH3ClO
66.45 (Remember that chlorine’s mass does not get rounded, you have to use 34.45 g/mol)
C2H8N2
60
C3H9O3P
124
10.
What is the mass of 0.25 mol of potassium nitrate, KNO3? Circle the correct answer. 1 pt.
a) 17.3 g
c) 69.0 g
b) 25.3 g
d) 101.0 g
Answer: b
3
11.
12.
13.
14.
What is the mass of 0.45 mol of 3-aminobutane-1,2,4-triol, C4H11NO3? Circle the correct
answer. 1 pt.
a) 54.45 g
c) 99.0 g
b) 20.3 g
d) 161.0 g
Answer: a
What is the mass of 1.25 mol of butan-1-amine C4H11N? Circle the correct answer. 1 pt.
a) 91.25 g
c) 199.0 g
b) 300.3 g
d) 71.0 g
Answer: a
What is the mass of 2.35 mol of adenine C5H5N5? Circle the correct answer. 1 pt.
a) 491.25 g
c) 199.0 g
b) 245.31 g
d) 317.25 g
Answer: d
How many moles are present in 100 g of (NH4)2SO4? Circle the correct answer. 1 pt.
a) 1.32 mol
c) 1.14 mol
Answer: b
b) 0.76 mol
15.
d) 0.88 mol
How many moles are present in 150g of CH5O3P? Circle the correct answer. 1 pt.
a) 2.32 mol
c) 1.24 mol
Answer: b
b) 1.56 mol
16.
d) 1.78 mol
How many moles are present in 113 g of hexane-2,3,4-triol (C6H14O3) ? Circle the correct
answer. 1 pt.
a) 0.84 mol
c) 0.64 mol
b) 0.56 mol
d) 0.78 mol
Answer: a
4
17.
18.
How many moles are present in 234g of 2-(dimethylamino) pentan-3-ol (C7H17NO)? Circle
the correct answer. 1 pt.
a) 1.79 mol
c) 2.64 mol
b) 0.56 mol
d) 1.68 mol
Answer: a
You are to prepare 300 mL of an aqueous solution of sodium hydroxide,
NaOH that will have a concentration of 0.8 mol/L.
What mass of NaOH do you need? Circle the correct answer. 1 pt.
a) 0.24 g
c) 9.6 g
b) 6.0 g
d) 32 g
Answer: c
19.
You are to prepare 150 mL of an aqueous solution of triphenylphosphine
C18H15P that will have a concentration of 1.25 mol/L.
What mass of C18H15P do you need? Circle the correct answer. 1 pt.
a) 32.24 g
c) 49.13 g
b) 26.02 g
d) 31.71 g
Answer: c
20.
21.
You are to prepare 75 mL of an aqueous solution of diethyl phosphonite
C4H11O2P that will have a concentration of 0.735 mol/L.
What mass of C4H11O2P do you need? Circle the correct answer. 1 pt.
a) 2.24 g
c) 9.13 g
b) 6.73 g
d) 5.71 g
Answer: b
You are to prepare 1.2 L of an aqueous solution of uracil
C4H4N2O2 that will have a concentration of 1.86 mol/L.
What mass of C4H4N2O2 do you need in kilograms? Circle the correct answer. 1
pt.
a) 0.25 Kg
c) 1.13 Kg
Answer: a
b) 0.73 Kg
d) 0.81 Kg
5
22.
What is the concentration of a solution of MgSO4 when 125 g of MgSO4 are dissolved to form
2.5 L of solution? 1 pt.
a) 0.38 mol/L
c) 2.40 mol/L
Answer: b
b) 0.42 mol/L
23.
24.
d) 2.60 mol/L
What is the concentration of a solution of CHKO2 when 200 g of CHKO2 are dissolved to form
0.85 L of solution? 1 pt.
a) 2.38 mol/L
c) 3.45 mol/L
b) 5.02 mol/L
d) 2.80 mol/L
Answer: d
500 mL of a 4 mol/L solution are diluted to form a 1 mol/L solution. What volume of water is
added to the original solution? 2 pts.
Step1 : Given
Step2 :
Step3 :
C1 : 4 mol/L
C1V1 = C2V2
Water = V2 – V1
V1 : 0.5 L
4 x 0.5 = 1 x V2
= 2 – 0.5
C2 : 1 mol/L
V2 = 2 L
= 1.5 L
V2 ?
Water ?
6
25.
250 mL of a 3.13 mol/L solution are diluted to form a 2.25 mol/L solution. What volume of
water is added to the original solution? 2 pts.
Step1 : Given
Step2 :
Step3 :
C1 : 3.13 mol/L
C1V1 = C2V2
Water = V2 – V1
V1 : 0.25 L
3.13 x 0.25 = 2.25 x V2
= 0.348 – 0.24
C2 : 2.25
V2 = 0.348 L
= 0.098 L
V2 ?
Water ?
26.
The lab technician is asked to prepare 2 L of 0.3 mol/L HNO3 solution. He has a stock supply
of 12 mol/L HNO3 solution. How much of the stock solution does he need? 2 pts.
Step1 : Given
Step2 :
C1 : 12 mol/L
C1V1 = C2V2
V1 : ?
12 x V1 = 0.3 x 2
C2 : 0.3 mol/L
V2 = 0.05 L
V2 : 2 L
27.
What is the mass (g) of 0.45 mol of each of the following compounds? 6 pts.
a. H4Al2O4
c. AlCl3
e. AlNaO2
54.9
60
36.9
b. Al2O3
d. H2Fe2O3
f. CaCO3
45.9
72.9
45
7
28.
How many moles are present in 200 g of each of the following compounds? 6 pts.
a. SnF4
c. AlCl3
f. PbO2
0.94
1.41
1.41
0.84
You are to prepare 150 mL of an aqueous solution with the following compounds. Each
solution will have a concentration of 3.45 mol/L. What mass (g) of each of the following
compounds do you need? 6 pts.
a. H4Al2O4
b. Al2O3
63.14
c. AlCl3
d. H2Fe2O3
69.01
e. AlNaO2
30.
d. P2O5
1.50
e. CrBr2
29.
b. Na2O4S
1.03
f. CaCO3
42.44
52.79
83.84
51.75
What will be the concentration (mol/L) of the following solutions when 120 g of each
compound is dissolved in 1.29 mL? 6 pts.
a.
Baking Soda: NaHCO3
1107.42
b.
Liquid bleach: NaClO
1249.47
c.
Solid bleach: NaBHO3
1120.76
d.
Borax: Na2B4O7 • H2O
422.83
e.
Chloroform: CHCl3
779.42
f.
Laughing gas: N2O
31.
2114.16
Give the formula to the following names. 4 pts.
a) Magnesium nitride
Mg3N2
b) Carbon tetrachloride
CCl4
c) Aluminium sulphide
Al2S3
d) Calcium phosphide
Ca3P2
8
32.
You are given 35 g of MgF2 dissolved in water at a concentration of 2.5 mol/L. Calculate the volume of water
used. 2 pts.
Step1 : Given
Step2 :
Step3 :
m: 35 g
n: m/mMm
V = n /C
mMm: 62 g/mol
: 35 g / 62 g/mol
= 0.56 mol / 2.5 mol/L
C: 2.5 mol/L
: 0.56 mol
= 0.224 L
V?L
___m____
n x mMm
n ? mol
33.
___n___
_C x V
Find the solution concentration in g/mL of dissolving 0.256 mol of Na2S in 0.4 L of water. 2 pts.
Step1 : Given
Step2 :
Step3 :
C ? g/mL
m = n x mMm
C=m/V
n= 0.256 mol
= 0.256 mol x 78 g/mol
= 19.97 g / 400 mL
m? g
= 19.97 g
= 0.050 g /mL
___m____
n x mMm
V: 0.4 L
mMm: 78 g/mol
___m___
_C x V
9
34.
What is the final concentration in mol/L of a solution if initially it had 500 mL concentrated at 2 mol/L and you
added 2.5 L to that solution? 2 pts.
Step1 : Given
Step2 :
C2?
C1V1 = C2V2
V1: 0.5 L
2 x 0.5 = C2 x 3
C2: 2 mol/L
C2 = 0.3 mol/L
V2: 2.5 L + 0.5 L
:3L
35.
What volume of distilled water must be added to 200 mL of an NaOH solution concentrated at 1.5 mol/L to
dilute it to 0.4 mol/L? 2 pts.
Step1 : Given
Step2 :
Step3 :
Water ?
C1V1 = C2V2
Water = V2 – V1
V1: 0.2 L
1.5 x 0.2 = 0.4 x V2
= 0.75- 0.2
C1: 2 mol/L
V2 = 0.75 L
= 0.55 L
C2: 0.4 mol/L
V2 ?
36.
Find the concentration in g/mL of dissolving 2.5 mol of NaBr in 3 L of water. 2
Step1 : Given
Step2 :
Step3 :
C ? g /mL
m = n x mMm
C = m/V
pts.
n: 2.5 mol
= 2.5 mol x 103 g/mol
= 257.5 / 3000
V: 3 L: 3000 mL
= 257.5 g
= 0.0857 g /mL
___m___
_C x V
m?
mMm: 103 g/mol
___m____
n x mMm
10
37.
You are given 60 g of CaCl2 dissolved in water at a concentration of 1.8 mol/L. Calculate the volume of water
used. 2 pts.
Step1 : Given
Step2 :
Step3 :
m: 60 g
n = m/mMm
V = n /C
mMm: 110.9 g/mol
= 60/110.9
= 0.541/1.8
C: 1.8 mol/L
= 0.541 mol
= 0.301 L
___m____
n x mMm
V?
n?
38.
___n___
_C x V
Find the solution concentration in g/mL of dissolving 0.345 mol of Li2O in 0.6 L of water.
Step1 : Given
Step2 :
Step3 :
C ? g/mL
m = n x mMm
C = m/V
n: 0.345 mol
= 0.345 x 30
= 10.35/600
mMm: 30 g/mol
= 10.35 g
= 0.0173 g/mL
V: 600 mL
39.
2 pts.
___m____
n x mMm
___m___
_C x V
What is the final concentration in mol/L of a solution if initially it had 400 mL concentrated at 3 mol/L and you
added 4.5 L to that solution? 2 pts.
Step1 : Given
Step2 :
C2 ?
C1V1=C2V2
V1: 400 mL: 0.4 L
3 x 0.4 = C2 x 4.9
C1: 3 mol/L
C2 = 0.24 mol/L
V2: 0.4+4.5: 4.9 L
11
40.
What volume of distilled water must be added to 150 mL of an CaCO3 solution concentrated at 0.250 g/mL to
dilute it to 0.5 mol/L? 2 pts.
Step1 : Given
Step2 :
Step3 :
Water ?
Convert C2 into g/mL
C1V1=C2V2
V1: 150 mL
m = n x mMm
0.25 x 150 = 0.05 x V2
C1: 0.25 g/mL
= 0.5 x 100 = 50 g
C2: 0.5 mol/L
C2 = 50 g / 1000 mL
V2 ?
41.
= 0.05 g /mL
___m___
_C x V
V2 = 750 mL
___m____
n x mMm
Water = V2 – V1
= 750 – 150 = 600 mL
Find the mass in grams in 75 mL of Al2O3 solution knowing that the concentration of this solution is 2.67 g/ L?
pts.
Step1 : Given
Step2 :
m?g
m=CxV
V: 75 mL: 0.075 L
= 2.67 x 0.075
C: 2.67 g/L
= 0.200 g
___m___
_C x V
12
2
42.
43.
2 pts.
If you were given 24 mg of CHCl3 in 175 mL, what is the concentration in g/L?
Step1 : Given
Step2 :
m: 24 mg: 0.024 g
C = m/V
V: 175 mL: 0.175 L
= 0.024/0.175
C?
= 0.137 g/L
___m___
_C x V
Which of the following is the mass in grams in 75 mL of Al2O3 solution knowing that the concentration of this
solution is 2.67 mol/ L? 2 pts.
Step1 : Given
Step2 :
Step3 :
C: 2.67 mol/L
n=CxV
m = n x mMm
V: 0.075 L
= 2.67 mol/L x 0.075 L
= 0.200 x 102
m?
= 0.200 mol
= 20.43 g
___n___
_C x V
n?
mMm: 102 g/mol
___m____
n x mMm
13
44.
If you were given 24 g of CHCl3 in 175 mL, what is the molarity (molar concentration, mol/ L) of this solution?
pts.
Step1 : Given
Step2 :
Step3 :
m: 24 g
n = m / mMm
C=n/V
V: 0.175 L
= 24 / 119.35
= 0.201 / 0.175
C?
= 0.201 mol
= 1.15 mol/L
___n___
_C x V
n?
___m____
n x mMm
mMm: 119.35
g/mol
45.
Convert 25 % (25g/100mL) of Mg(OH)2 (aq) into molarity (mol/ L). 2
pts.
Step1 : Given
Step2 :
Step3 :
m: 25 g
n = m / mMm
C=n/V
V: 0.1 L
= 25 / 58
= 0.43 / 0.1
n?
= 0.43 mol
= 4.3 mol/L
___n___
_C x V
mMm: 58 g
___m____
n x mMm
14
2
46.
What is the final concentration of a solution if initially it had 2L concentrated at 8 mol/L and you added 3 L to that
solution? 2 pts.
Step1 : Given
Step2 :
C2 ?
C1V1 = C2V2
V1: 2 L
8 x 2 = C2 x 5
C1: 8 mol/L
C2 = 3.2 mol/L
V2: 3+2: 5L
47.
What volume of distilled water must be added to 100 mL of an NaOH solution concentrated at 3 mol/L to dilute it
to 1 mol/L? 2 pts.
Step1 : Given
Step2 :
Step3 :
Water ?
C1V1 = C2V2
Water = V2-V1
V1: 100 mL: 0.1L
3 x 0.1 = 1 x V2
= 0.3 – 0.1
C1: 3 mol/L
V2 = 0.3 L
= 0.2 L
V2 ?
C2: 1 mol/L
15
48.
When drawing the Newton-Lewis diagram for the combination of Oxygen and Nitrogen, how many electrons are
being shared in total? 1 pt.
Covalent bond formed by two non-metals that SHARE electrons.
N3 O2
N2O3
Double bonds
N
O
N
O
Single bond
O
Single bond
O N O N O
Answer: 12 electrons are being
shared.
Double bonds
16
49.
Which of the following are covalent compound(s)? Circle
the correct answer. 1 pts.
a. H2O
b. NaCl
Answer: a and d
c. MgF2
d. NI3
50.
Draw the Newton-Lewis structure for Mg3P2.
2 pts.
Ionic bond formed by a metal with a non-metal where there is a transfer of electrons.
Mg+2 P-3
P
Mg
Mg3P2
P
Mg
Mg
Mg P Mg P Mg
17
51.
Draw the Newton-Lewis diagram for the compound formed between Ca and C. 2
pts.
Ionic bond formed by a metal with a non-metal where there is a transfer of electrons.
Ca+2 C-4
Ca4C2
Ca2C
C
Ca
Ca
Ca C Ca
18
52.
What volume of water do you need to make a 25.5% salt water solution if you are given 30 g of salt?
Step1 : Given
Step2 :
C: 25.5 g/ 100 mL
: 0.255 g/mL
V = m/C
= 30 g / 0.255 g/mL
m: 30 g
V?
53.
___m___
_C x V
= 117.65 mL
Which are ionic compound(s)?
Circle the correct answer. 1 pt.
a. NaCl
b. CCll4
Answer: a and d
c. NI3
d. CaO
54.
Draw the Newton-Lewis structure when you combine barium with chlorine. 2
Ba
+2
Cl
-1
pts.
BaCl2
Ba
Cl
Cl
Cl
Ba Cl
19
2 pts.
55.
Draw the he Newton-Lewis structure when you combine phosphorous with carbon.
2 pts.
Covalent bond formed by two non-metals that SHARE electrons.
C+4 P-3
C 3P 4
P
P
C
P
P
C
C
P C P C P C P
56.
the mass in grams in 300 mL of NaOH solution knowing that the concentration of this
solution is 7.6 mol/ L. 2 pts.
Find
Step1 : Given
Step2 :
Step3 :
m?
n=CxV
m = n x mMm
V: 0.3 L
= 7.6 mol/L x 0.3 L
= 2.28 mol x 40 g/mol
C: 7.6 mol/L
= 2.28 mol
= 91.2 g
___n___
_C x V
n?
mMm: 40 g/mol
___m____
n x mMm
20
57.
the mass in grams in 150 mL of HF solution knowing that the concentration of this
solution is 6 mol/ L. 2 pts.
Find
Step1 : Given
Step2 :
Step3 :
m?
n=CxV
m = n x mMm
V: 150 mL: 0.15 L
= 0.15 x 6
= 0.9 x 20
C: 6 mol/L
= 0.9 mol
= 18 g
n?
___m____
n x mMm
mMm: 20 g/mol
58.
___n___
_C x V
the mass in grams in 75 mL of Al2O3 solution knowing that the concentration of this
solution is 2.67 mol/ L. 2 pts.
Find
Step1 : Given
Step2 :
Step3 :
m?
n=CxV
m = n x mMm
V: 75 mL: 0.075 L
= 2.67 x 0.075
= 0.200 x 102
C: 2.67 mol/L
= 0.200 mol
= 20.4 g
___n___
_C x V
n?
mMm: 102 g/mol
___m____
n x mMm
21
59.
the mass in grams in 120 mL of AlCl3 solution knowing that the concentration of this
solution is 1.35 mol/ L. 2 pts.
Find
Step1 : Given
Step2 :
Step3 :
m?
n=CxV
m = n x mMm
V: 120 mL: 0.12 L
= 1.35 x 0.12
= 0.162 x 133.35
C: 1.35 mol/L
= 0.162 mol
= 21.6 g
n?
___m____
n x mMm
mMm: 133.35 g/mol
60.
___n___
_C x V
the number of moles in 120 mL of H2Fe2O3 solution knowing that the concentration of
this solution is 250 g/ L. 2 pts.
Find
Step1 : Given
Step2 :
Step3 :
n?
m=CxV
n = m / mMm
V: 120 mL: 0.12 L
= 250 x 0.12
= 30 / 162
C: 250 g/L
= 30 g
= 0.185 mol
___m___
_C x V
m?
mMm: 162 g/mol
___m____
n x mMm
22
61.
the number of moles in 300 mL of AlNaO2 solution knowing that the concentration of this
solution is 75 g/ L. 2 pts.
Find
Step1 : Given
Step2 :
Step3 :
n?
m=CxV
n = m / mMm
V: 300 mL: 0.3 L
= 75 x 0.3
= 22.5 / 82
C: 75 g/L
= 22.5 g
= 0.274 mol
___m___
_C x V
m?
___m____
n x mMm
mMm: 82 g/mol
62.
the number of moles in 225 mL of CaCO3 solution knowing that the concentration of this
solution is 135 g/ L. 2 pts.
Find
Step1 : Given
Step2 :
Step3 :
n?
m=CxV
n = m / mMm
V: 225mL: 0.225 L
= 135 x 0.225
= 30.4 / 100
C: 135 g/L
= 30.4 g
= 0.304 mol
___m___
_C x V
m?
mMm: 100 g/mol
___m____
n x mMm
23
63.
the number of moles in 400 mL of CaCO3 solution knowing that the concentration of this
solution is 200 g/ L. 2 pts.
Find
Step1 : Given
Step2 :
Step3 :
n?
m=CxV
n = m / mMm
V: 400 mL: 0.4 L
= 200 x 0.4
= 80 / 100
C: 200 g/L
= 80 g
= 0.80 mol
___m___
_C x V
m?
___m____
n x mMm
mMm: 100 g/mol
64.
If you were given 16 g of NaBHO3 in 200 mL, what is the molarity (molar concentration mol/
L) of this solution? 2 pts.
Step1 : Given
Step2 :
Step3 :
m: 16 g
n = m/mMm
C = n/V
V: 200 mL: 0.2 L
= 16 / 83
= 0.193 / 0.2
n?
= 0.193 mol
= 0.964 mol/L
C ? mol/L
___n___
_C x V
mMm: 83 g/mol
65.
___m____
n x mMm
If you were given 24 g of CHCl3 in 175 mL, what is the molarity (molar concentration mol/ L)
of this solution? 2 pts.
Step1 : Given
Step2 :
Step3 :
m: 24 g
n = m/mMm
C = n/V
V: 175 mL: 0.175 L
= 24 / 119.35
= 0.201 / 0.175
n?
= 0.201 mol
= 1.15 mol/L
C ? mol/L
mMm: 119.35 g/mol
___m____
n x mMm
___n___
_C x V
24
66.
If you were given 50 g of N2O in 154 mL, what is the molarity (molar concentration mol/ L) of
this solution? 2 pts.
Step1 : Given
Step2 :
Step3 :
m: 50 g
n = m/mMm
C = n/V
V: 154 mL: 0.154 L
= 50 / 40
= 1.14 / 0.154
n?
= 1.14 mol
= 7.38 mol/L
___m____
n x mMm
C ? mol/L
___n___
_C x V
mMm: 44 g/mol
67.
If you were given 100 g of NaClO in 250 mL, what is the molarity (molar concentration mol/ L)
of this solution? 2 pts.
Step1 : Given
Step2 :
Step3 :
m: 100 g
n = m/mMm
C = n/V
V: 250 mL: 0.250 L
= 100 / 74.45
= 1.34 / 0.250
n?
= 1.34 mol
= 5.37 mol/L
C ? mol/L
___n___
_C x V
mMm: 74.45 g/mol
68.
___m____
n x mMm
If you were given 55 g of NaHCO3in 300 mL, what is the molarity (molar
concentration mol/ L) of this solution? 2 pts.
Step1 : Given
Step2 :
Step3 :
m: 55 g
n = m/mMm
C = n/V
V: 300 mL: 0.300 L
= 55 / 84
= 0.655 / 0.3
n?
= 0.655 mol
= 2.18 mol/L
C ? mol/L
mMm: 84 g/mol
___m____
n x mMm
___n___
_C x V
25
69.
Convert 10 % AlCl3 (aq) into molarity (mol/ L). 2 pts.
Step1 : Given
Step2 :
Step3 :
10 % : 10 g /100 mL
: 0.10 g/mL
n = m/mMm
C = n/V
= 0.10 / 133.35
= 0.00075 / 0.001
= 0.00075 mol
= 0.75 mol/L
___m____
n x mMm
n?
V?L
___n___
_C x V
mMm: 133.35 g/mol
70.
Convert 9 % H4Al2O4 (aq) into molarity (mol/ L). 2 pts.
Step1 : Given
Step2 :
Step3 :
9 % : 9 g /100 mL
: 0.09 g/mL
n = m/mMm
C = n/V
= 0.09 / 122
= 0.00074 / 0.001
= 0.00074 mol
= 0.74 mol/L
___m____
n x mMm
n?
V?L
___n___
_C x V
mMm: 122 g/mol
71.
Convert 25 % Mg(OH)2 (aq) into molarity (mol/ L). 2 pts.
Step1 : Given
Step2 :
Step3 :
25 % : 25 g /100 mL
: 0.25 g/mL
n = m/mMm
C = n/V
= 0.25 / 58
= 0.43 / 0.001
= 0.43 mol
= 4.3 mol/L
___m____
n x mMm
n?
V?L
mMm: 40 g/mol
___n___
_C x V
26
72.
Convert 18 % (CH3)2CHOH (aq) into molarity (mol/ L). 2 pts.
Step1 : Given
Step2 :
Step3 :
18 % : 18 g /100 mL
: 0.18 g/mL
n = m/mMm
C = n/V
= 0.18 / 60
= 0.003 / 0.001
= 0.003 mol
= 3.0 mol/L
___m____
n x mMm
n?
V?L
___n___
_C x V
mMm: 60 g/mol
The following numbers are considered to be advanced problems. They are a good practice for
you to complete when you are comfortable with molarity.
73.
What amount of solvent must be added to a solution that contains 200 g of FeS2 in 200 mL of
water to obtain a final concentration of 2 mol/ L? 2 pts.
Step1 : Given
Step2 :
Step3 :
Step4 :
V1: 200 mL: 0.2 L
n = m/mMm
C1V1= C2V2
Water = V2-V1
C1 ?
= 200 / 120
8.3 x 0.2 = 2 x V2
= 0.83 – 0.2
n?
= 1.7 mol
V2 = 0.83 L
= 0.63 L
C2: 2 mol/L
C1= n/V1
m: 200 g
= 1.7 / 0.2
V2 ?
= 8.3 mol/L
Water ?
mMm: 120 g/mol
27
74.
What amount of solvent must be added to a solution that contains 75 g of Na 2B4O7 • H2O in
100 mL of water to obtain a final concentration of 0.25 mol/ L? 2 pts.
Step1 : Given
Step2 :
Step3 :
Step4 :
V1: 100 mL: 0.1 L
n = m/mMm
C1V1= C2V2
Water = V2-V1
C1 ?
= 75 / 220
3.41 x 0.1 = 0.25 x V2
= 1.364 – 0.1
n?
= 0.341 mol
V2 = 1.364 L
= 1.264 L
C2: 0.25 mol/L
C1= n/V1
m: 75 g
= 0.341 / 0.1
V2 ?
= 3.41 mol/L
Water ?
mMm: 220 g/mol
28
75.
What amount of solvent must be added to a solution that contains115 g of HCl in 240 mL of
water to obtain a final concentration of 0.56 mol/ L? 2 pts.
Step1 : Given
Step2 :
Step3 :
Step4 :
V1: 240 mL
: 0.24 L
n = m/mMm
C1V1= C2V2
Water = V2-V1
= 115 / 36.45
13.15 x 0.24 = 0.56 x V2
= 5.64 – 0.24
= 3.16 mol
V2 = 5.64 L
= 5.40 L
C1 ?
n?
C2: 0.56 mol/L
C1= n/V1
m: 115 g
= 3.16 / 0.24
V2 ?
= 13.15 mol/L
Water ?
mMm: 36.45 g/mol
29
76.
What amount of solvent must be added to a solution that contains265 g of PbO 2 in 120 mL of
water to obtain a final concentration of 3 mol/ L? 2 pts.
Step1 : Given
Step2 :
Step3 :
Step4 :
V1: 120 mL
: 0.12 L
n = m/mMm
C1V1= C2V2
Water = V2-V1
= 265 / 239
9.24 x 0.12 = 3 x V2
= 0.37 – 0.12
= 1.11 mol
V2 = 0.370 L
= 0.25 L
C1 ?
n?
C2: 3 mol/L
C1= n/V1
m: 265 g
= 1.11 / 0.12
V2 ?
= 9.24 mol/L
Water ?
mMm: 239 g/mol
30
77.
What amount of solvent must be added to a solution that contains140 g of CrBr2 in 80 mL of
water to obtain a final concentration of 4.1 mol/ L? 2 pts.
Step1 : Given
Step2 :
Step3 :
Step4 :
V1: 80 mL
: 0.08 L
n = m/mMm
C1V1= C2V2
Water = V2-V1
= 140 / 212
8.25 x 0.08 = 4.1 x V2
= 0.66 mol
V2 = 0.161 L
= 0.161 – 0.08
C1 ?
= 0.081 L
n?
C2: 4.1 mol/L
C1= n/V1
m: 140 g
= 0.66 / 0.08
V2 ?
= 8.25 mol/L
Water ?
mMm: 212 g/mol
31
78.
What amount of solvent must be added to a solution that contains 230 g of SnF 4 in 60 mL of
water to obtain a final concentration of 1.25 mol/ L? 2 pts.
Step1 : Given
Step2 :
Step3 :
Step4 :
V1: 60 mL
: 0.06 L
n = m/mMm
C1V1= C2V2
Water = V2-V1
= 230 / 195
19.66 x 0.06 = 1.25 x V2
= 1.18 mol
V2 = 0.944 L
= 0.944 – 0.06
C1 ?
= 0.884 L
n?
C2: 1.25 mol/L
C1= n/V1
m: 230 g
= 1.18 / 0.06
V2 ?
= 19.66 mol/L
Water ?
mMm: 195 g/mol
32
79.
What amount of solvent must be added to a solution that contains140 g of C 16H36N in 20 mL
of water to obtain a final concentration of 0.15 mol/ L? 2 pts.
Step1 : Given
Step2 :
Step3 :
Step4 :
V1: 20 mL
: 0.02 L
n = m/mMm
C1V1= C2V2
Water = V2-V1
= 140 / 242
28.93 x 0.02 = 0.15 x V2
= 0.579 mol
V2 = 3.86 L
= 3.86 – 0.02
C1 ?
= 3.84 L
n?
C2: 0.15 mol/L
C1= n/V1
m: 140 g
= 0.579 / 0.02
V2 ?
= 28.93 mol/L
Water ?
mMm: 242 g/mol
33