1
CHEMISTRY 3U
Problem Type: Molecular Mass - % Composition - Simplest Formula
1. Calculate the molecular mass of
a) F2
b) Al2(SO4)3
c) CuSO4.5H2O
38 u
342 u
249.5 u
2. What is the mass of a) 5.0 moles of boron?
b) 0.25 moles of glucose, C6H12O6?
3. Calculate the number of moles in 21 g of aluminum.
How many aluminum atoms does this represent?
54 g
45 g
0.78 mol
4.7 x 1023 atoms
4. Determine the number of moles in 115 g of ethanol, C2H5OH.
2.5 mol
5. How many moles of atoms are there in 6 moles of CH3COOH?
6. Calculate % a) of Ca in CaCO3.
b) composition of CaCO3.
c) of water in Na2CO3.10H2O.
40%
12% C, 48% O
62.9%
7. Calculate the simplest formula for the compound whose percentage (by mass)
composition is: 20.00% Mg, 26.67% S, 53.33% O.
MgSO4
8. 9.23 g of calcium are heated in an excess of nitrogen. The final product has a
mass of 11.38 g. Determine its formula.
Ca3N2
9. Many crystalline compounds contain water of hydration that is driven off when the compound is
heated. The loss of mass in heating can be used to determine the simplest formula. For example, a
hydrate of cobalt chloride, CoCl2.XH2O, weighing 0.809 g was heated until all the combined water
was expelled. The dry powder remaining weighed 0.442 g. Determine the formula of the hydrate.
10. A sample of an organic compound containing carbon, hydrogen and oxygen (C xHyOz), which
weighed 12.13 mg, gave 30.6 mg of CO2 and 5.36 mg of H2O on combustion. Determine the
simplest (empirical) formula of this compound.
CaCl2.6H2O
C7H6O2
Problem Type: Problems based on the Gas Laws
1. An automobile tire has a gauge pressure of 231 kPa at 20 oC.
What is the gauge pressure if the temperature rises to 40oC?
247 kPa
2. To what temperature must a gas be cooled at constant pressure so that it would occupy
half the volume it occupies at 100oC?
-86oC
3. 16 g of oxygen was introduced into an evacuated 10.0 litre flask at 350 K.
Calculate the pressure in the container.
146 kPa
4. A low pressure easily achieved with a diffusion pump and a mechanical vacuum pump is
1.33 x 10-7 kPa. Calculate the number of molecules still present in 1 mL of gas at this pressure and
at -196oC. (Assume that the gas will not condense at the temperature of liquid nitrogen, -196oC.)
5. A student collects 265 mL of a gas over mercury at 25oC and 100 kPa.
What is the volume at standard conditions (STP)?
240 mL
6. What is t he volume of one mole of any (ideal) gas at 27oC and 98.6 kPa?
25.3 L
2
7. What is the density of ammonia gas, NH3, at 67oC and 106.6 kPa?
8. a) What is the molecular mass of a gas if a 0.894 g sample in in a 600 mL bulb has a pressure
of 53.3 kPa at 20oC?
b) If the simplest formula of the gas in 8 a) had been found to be CH 3F, what would be its
molecular formula?
0.641 g/L
68.1 g/mol
C2H6F2
Problem Type: Problems based on the Gas Laws
1. What is the apparent molecular mass of air, assuming that air contains 78% nitrogen, 21% oxygen
and 1% argon by volume?
29.0 g/mol
2. A 250 mL flask is filled with oxygen, collected over water at a pressure of 730 mmHg and a
temperature of 25oC. What will be the volume of this oxygen sample, dry, at standard
conditions? The vapour pressure of water at 25o C is 24 mmHg.
213 mL
3. Calculate the volume of a mixture of 0.040 mol of nitrogen and 0.010 mol of oxygen at 300 K
and 1 atm pressure.
1.2 L
4. A mixture of 2.00 g helium, 7.00 g nitrogen, 10.0 g argon and 16.0 g oxygen occupy a container.
The total internal pressure is 1.80 x 103 mmHg. Determine the partial pressure of each gas.
PN = 40 kPa
2
5. A steel cylinder whose volume is 2.00 litres if filled with nitrogen at 22.0o C and 98.6 kPa.
2.00 litres of neon and 4.00 litres of helium, each measured at 36.0 oC and 104 kPa are then forced
into the cylinder. If the cylinder is then cooled to -10o C, what is the total pressure exerted by the
mixture of gases?
3.5 102 kPa
Problem Type: Problems based on Concentrations of Solutions
1. Calculate the number of grams of potassium permanganate, KMnO4 required to prepare 6.0 L
of a 0.050 M solution.
47 g
2. What volume of 18 M acid is needed to prepare 5.0 litres of 6.0 M acid?
1.7 L
3. How would you prepare 150 mL of 0.40 mol/L sodium sulphate from a 2.0 mol/L solution?
4. Express in milligrams per millilitre (mg/mL) the concentration of a 0.050 mol/L magnesium
bromide solution. Calcuate the mass of magnesium bromide present in 25 mL of this solution.
9.2 mg/mL
230 mg
5. The density of a 7.0 mol/L HCl solution is 1.11 g/mL. Find the percentage of HCl (by mass)
in the 7.0 mol/L solution.
23%
6. If 3.0 litres of 6.0 mol/L HCl are added to 2.0 litres of 1.5 mol/L HCl, what is the resulting
concentration? (Assume the final volume to be exactly 5.0 litres).
4.2 mol/L
7. Calculate the molarity of a stock sulphuric acid solution which has a density of 1.84 g/mL and
is 92.0 % by mass H2SO4.
17.3 mol/L
8. Describe completely how you would prepare 250 mL of a 1.5 mol/L solution of H 2SO4 from
the stock acid solution in question #7.
9. The concentration of certain solutions of spirits is stated on the label in terms of “proof”.
In the United States, 100 proof is defined as containing one half its volume pure alcohol
(C2H5OH at 15oC has a density of 0.793 g/mL. Calculate the molarity of a bottle of 86-Proof.
Problem Type: Equation Problem - Mass-Mass Relationship
7.4 mol/L
1.
2.
3.
4.
5.
6.
7.
3
How many grams of calcium carbide are needed to produce 6.5 g of acetylene?
CaC2 + 2H2O
C2H2 + Ca(OH)2
16 g
How many grams of nitrogen dioxide may theoretically be produced when copper reacts completely
with 21 g of concentrated nitric acid? (Assume that the concentrated acid is 100% HNO 3).
Cu + 4HNO3
Cu(NO3)2 + 2H2O + 2NO2
7.7 g
Enough sulphuric acid was added to 100 mL of a solution of barium chloride to convert all the
barium to insoluble barium sulphate. If 0.854 g of barium sulphate was formed, calculate the mass
of barium chloride in 100 mL of solution.
BaCl2 + H2SO4
BaSO4 + 2HCl
0.762 g
How much ethyl alcohol, C2H5OH, can theoretically be produced by the alcoholic fermentation
of 5.0 kg of dextrose sugar, C6H12O6?
C6H12O6 zymase > 2C2H5OH + 2CO2
2.6 kg
How much limestone, which contains 90% calcium carbonate, must be used to produce
5.0 x 102 kg of calcium oxide?
CaCO3
CaO + CO2
9.9 x 102 kg
Nitric acid reacts with silver according to the eqauation
4HNO3 + 3Ag
3AgNO3 + NO + 2H2O
Calculate the number of grams of silver nitrate and nitric oxide produced when 126 g of HNO 3
is added to 108 g of Ag.
The purity of a 0.617 g sample of impure FeS was tested by passing the H2S produced into a dilute
solution of AgNO3. The precipitate of the Ag2S produced was 1.322 g. Calculate the % of FeS in
the original sample.
FeS + 2HCl
H2S + FeCl2
H2S + 2AgNO3
Ag2S 2HNO3
Problem Type:
1.
Equation Problem
-
170 g AgNO3
10.0 g of NO
76.1%
Volume-Volume Relationship
Propane can be oxidized to carbon monoxide according to the equation
C3H8(g)
+
3.50 2(g)
3CO(g)
+
4H2O(g)
a)
b)
c)
d)
How many litres of propane at STP are required to produce 9.0 L of CO at STP?
If 15 L of O2 at STP are used, how many litres of propate at STP will be consumed?
If 10 L each of oxygen and propane are mixed at STP, how many litres of CO at STP are produced?
How many litres of CO at 27oC and 750 mmHg could be produced when 9.0 L of propane at the same
temperature and pressure reacts completely?
e) How many litres of CO at 27oC and 750 mmHg could be produced when 9.0 L of propane at STP
completely reacts?
f) How many litres of gaseous substances at STP will be present after 34 L of propane and 115 L of
oxygen at STP are allowed to react until the reaction is complete?
g) How many litres of air at STP are needed to react with 2.0 L of propane at STP?
(Assume that air is 20% by volume oxygen).
2.
3.
A mixture composed of 32 mL of oxygen and 40 mL of hydrogen is exploded. Determine the volume of
gas which is left uncombined and name the gas.
3.0 L
4.3 L
8.6 L
27 L
3.0 x10 L
231 L
35 L
12 mL O2
Fluorine displaces oxygen from watr according to the following equation:
3F2 + 3H2O
6HF + O3
How many litres of ozone are produced when 30 litres of fluorine react with water?
10 L
Problem Type:
1.
2.
3.
4.
5.
4
Equation Problem
-
Mass-Volume Relationship
How many grams of aluminum are needed for the preparation of 90. litres of hydrogen at standard conditions?
2Al + 3H2SO4
Al2(SO4)3 + 3H2
7.2 g
How many litres of chlorine can be prepared at room conditions by reacting manganese dioxide with 6.0 g
of hydrogen chloride in the form of hydrochloric acid?
4HCl + MnO2
MnCl2 + 2H2O + Cl2
1.0 L
What mass of ammonium sulphate is needed for the preparation, at STP, of 2.0 litres of ammonia?
(NH4)2SO4 + Ca(OH)2
CaSO4 + 2NH3 + 2H2O
Calculate the number of litres of carbon dioxide, measured at STP, formed when 3.0 kg of coal, which is
60% carbon, burns completely in air.
C + O2
CO2
5.9 g
3.4 x 103 L
In the process of photosynthesis, plants use CO2 and water to produce sugars according to the reaction
12CO2 + 11H2O
C12H22O11 + 12O2
a) What volume of CO2 at 30oC and 101.3 kPa is used by a plant in making 500 g of sucrose, C12H22O11?
436 L
b) What volume of air is deprived of its normal amount of CO 2 in this process? (Air contains 0.04% CO2
by volume. Assume a pressure of 100.0 kPa and a temperature of 20 o C.)
106 L
6.
Ethyl alcohol, C2H5OH, is produced by the enzymatic action of yeast on sugar.
zymase > 2C H OH + 2CO
C6H12O6
2 5
2
What volume of CO2 at 96 kPa and 30o C is formed during the production of 500 L of alcohol that is
2.2 x 105
95% C2H5OH by mass? (The density of 95% C2H5OH is 0.80 g/mL).
NOMENCLATURE A. Name the following compounds.
1. Cu2SO3
2. Pb(MnO4)2
3. HF(aq)
4. (NH4)2SO4
5. Ca(HCO3)2
6. Be(NO2)2
7. HIO3(aq)
8. Al4C3
9.
10.
11.
12.
13.
14.
15.
16.
NOMENCLATURE
B.
Write a formula for each of the following:
1. gold(III) fluoride
14.
2. sodium chlorite
15.
3. stannic chloride
16.
4. aluminum bromate
17.
5. phosphorous acid
18.
6. ferrous chromate
19.
7. silver dichromate
20.
8. tin(II) oxalate
21.
9. acetic acid
22.
10. hydrosulphuric acid
23.
11. hypofluorous acid
24.
12. nitrogen triodide
25.
-
Binary Compounds, Acids, Bases and Salts
Cu(OH)2
KHC2O4
Ag2S2O3
Zn(IO4)2
H2CrO4(aq)
Sb2S3
Hg2(CH3COO)2
MnCO3
17. As(CN)3
18. HSCN(aq)
19. BN
20. Ba(BrO)2
21. Ca(H2PO4)2
22. AlH3
23. Fe2(CrO4)3
24. (NH4)2Cr2O7
Binary Compounds, Acids, Bases and Salts
manganese(III) hydroxide
aluminum acetate
zinc phosphide
carbon tetrachloride
boric acid
cobaltous borate
nickel(II) periodate
ammonium thiocyanate
ammoniun perchlorate
antimony(V) permanganate
chlorine VII) oxide
dichromic acid
5
SCH3U Exam Review #5
Balance the following equations:
1.
AgNO3 +
MgBr2
O2
AgBr
+
Mg(NO3)2
2.
No +
3.
P
4.
Al +
5.
C6H6 + O2
6.
Fe2(SO4)3
7.
Al(OH)3
+
H2SO4
Al2(SO4)3
+
H2 O
8.
Cu(OH)2
+
H3PO4
Cu3(PO4)2
+
H2 O
9.
MnO2 + H2SO4
+
10.
KMnO4 +
H2C2O4 +
11.
Cu
12.
Fe2(SO4)3
13.
Zn +
14.
Cr2O7-2
15.
ClO3-
+
16.
MnO2
+
17.
Fe+3
+
I-
18.
PbO2
+
Sn+2 + H+
+
NO2
I2
PI3
MnO2
Mn
CO2
+
KCl
I- +
H+
+
+
+ I2
MnSO4 +
H2SO4
Ag
Fe+3
SO4-2
+
Zn+2
H+
+
K2SO4
Cl2 +
SO4-2
Cr+3 +
H+
Cl-
+
Cl-
Mn+2
+
Fe+2
+
H2 O +
MnSO4 +
Cu+2 +
SO4-2
Br-
H2 O
FeSO4
+ Ag+
+
Al2O3
+
KI
H+ +
+
+
CO2 +
+
K2SO4
H2 O +
H2
I2
+
Br2
+
Cl2
H2 O
H2 O
+ H2 O
I2
Pb+2
+
Sn+4
+
H2 O
K2SO4