Download Chapter 4: Properties of Gases

PROBLEMS
1-
The density of CH4 gas at 25oC and 1.50 atm. is:
(a) 0.981 g/L
2-
(b)0.891 g/L
(b)0.345 atm
(b)280 torr
(d)110 torr
(b)2.0 g mol-1
(c)11.2 g mol-1
(d)44.0 g mol-1
(b)224 mL
(c)2584 mL
(d)7 mL
When the Kelvin temperature of a gas is halved and the pressure is held
constant, the volume:
(a) Doubles
7-
(c)140 torr
O2 gas is collected over water at 25oC. If the volume of the gas is 245
mL at a pressure of 758 torr, (v.p. of H2O = 23.8 torr). Thus the volume
of dry oxygen at STP is:
(a)2l7 mL
6-
(d)0.800 atm
If the density of gas X at STP is 1.965 g per liter, the molar mass of this
gas is:
(a)1.0 g mol-1
5-
(c)0.100 atm
A 50 mL sample of oxygen at 25oC and 120 torr and a 100 mL sample
of nitrogen at 25oC and 160 torr are both placed in a 200 mL flask at
25oC. What is the final pressure in the 200 mL flask?
(a)250 torr
4-
(d)0.700 g/L
A mixture of 40.0 g of oxygen and 40.0 g of helium gases has a total
pressure of 0.90 atm. The partial pressure of the oxygen in this mixture
is:
(a)0.799 atm
3-
(c)1.00 g/L
(b)Halves
(c)Remains constant
(d)Can not be determined
What is the molecular mass of a gas whose density is 3.79 g/L at 25oC
and a pressure of 729 torr?
(a)153
(b)97
(c)118
67
(d)64
8- Copper metal may be oxidized to a Cu1+ ion by the following equation:
2Cu + 2HCl  2CuCl + H2
If 6.4 g of Cu is oxidized, what volume of hydrogen (at STP) is evolved?
(a)22.4 L
9-
(b)12.2 L
(c)1.1 L
At extremely low pressure, the van der Waals equation for one mole
may be written as
(b) (P – a / v2)v = RT
(d) Pv = RT
(a) P(v + b) = RT
(c) (P – a / v2) (v + b) = RT
10-
60.0 mL of O2 was collected over water at a total pressure of 755 torr
and at a temperature of 25oC. The vapor pressure of water at 25oC is 24
torr. How many moles of O2 were collected?
(a)2.44 x 10-3 mol
(c)2.51 x 10-3 mol
11-
(b)4.81x1021
(c) 3.66x1021
(d)4.81x1018
A balloon filled with helium has a volume of 10,000 liters at
atmospheric pressure and 30oC. The weight (in kilograms) of helium
needed to fill the balloon is:
(a)
13-
(b)6.89 x 10-3 mol
(d)2.36 x 10-3 mol
The number of oxygen molecules in 150 mL flask at 1 torr pressure and
25oC is:
(a)6.02x1023
12-
(d)0.05 L
2.455
(b)
8.155
**(c) 1.610
(d)
0.963
The density (in g/L) of fluorine gas, F2(g), at STP is:
(a)1.35
(b)1.70
(c)0.85
(d)1.05
14-
70 g of a certain diatomic gas occupies 22.4 L at STP. What is this gas?
15-
(a)O2
(b)F2
(c)Cl2
(d)N2
If 6.4 g of Zn is oxidized according to the following equation:
Zn + 2HCl  ZnCl2 + H2
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What volume of hydrogen (at STP) is evolved?
(a)2.2 L
(b)12.2 L
(c)l.1 L
(d)0.05 L
16- How many liters of oxygen at STP are needed to combine with 1.50 L of
hydrogen at STP?
2H2 (g) + O2 (g)  2H2O(ℓ)
(a)2.24 L
17-
(b)1.11
(c)0.555
(d)16
(b)50.0 mL
(c)75.0 mL
(d) 7.5 mL
In the van der Waals equation of state for 1 mole of a non-ideal gas
(real gas), (P + a/V2)(V - b) = RT.
The effect of intermolecular forces is accounted for by which of the
following:
(a)
(c)
20-
(d)75 L
Consider the following chemical equation:
2NO2(g)  N2O4(g)
If 25.0 mL of NO2 gas is completely converted to N2O4 gas under the
same conditions. The volume of N2O4 will be:
(a)12.5 mL
19-
(c)1.50 L
The density of oxygen in g/L at 25oC and 0.85 atm is:
(a)2.22
18-
(b)0.35 L
P + a/V2
RT
(b)
(d)
V-b
A different value for R.
A gaseous sample has a density of 13.1 g/L and a pressure of 779 torr at
62oC. What is the molar mass of the gas?
(a)63.5
(b) 351.1
(c)46.8
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(d)93.6
21-
The volume of O2 required for the complete combustion of 125 g
octane (C8H18) to CO2 and H2O is:
2C8H18 (ℓ) + 25O2 (g)  16CO2 (g) + 18H2O (ℓ)
(a)153 L
22-
(b) 63.90 torr
(b)0.3344 L
(c)11.03 L
(b)4.06 g
(d) 5.05 l
(c)10.57 g
(d) 12.13 g
which of the following belongs to Charle's law?
(a) V  1/P(at constant T)
(c ) P  T (at constant V).
27-
(c)15.97 torr (d) 48.00 torr
The mass of 6.5 L of N2 gas at STP is:
(a)8.125 g
26-
(d) 351 L
The volume of 5 g of N2O gas occupied at 50oC and 12 atm is:
(a)0.251 L
25-
**(c) 307 L
A sample of gas was collected over water at 30oC to form a total
pressure of 1.01 atm in a volume of 500 mL. The gas was dried of
water and collected in a 1 L flask and found to have a pressure of 0.476
atm at 25oC. What is the vapor pressure of H2O at 30oC?
(a) 31.94 torr
23-
(b) 703 L
(b) V  T (at constant P).
(d) P  1/T (at constant V).
Which of the following formula belongs to Gay Lussac's law?
(a) V 1/P (at constant T)
(c)P  T (at constant V)
(b)V  T (at constant P)
(d)P  1/V (at constant T)
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PROBLEMS
1-
When comparing energies of a double and a single bond we find that
when we break a double bond
(a) A higher energy is given out.
(c)A higher energy is taken in.
2-
The combustion of glucose is described by:
C6H12O6(s) + 6O2(g) = 6CO2(g) + 6H2O(ℓ); H = 2.82 x 103 kJ
The mass of glucose (in grams) that must be burned to produce 47.0 kJ
of heat is:
(a)3.00
3-
(b)A lower energy is given out.
(d)A lower energy is taken in.
(b) 6.95
(c)4.29
(d)2.25
if Hreaction has a positive value, then
(a)Bonds broken are stronger than bonds formed.
(b)Bonds broken are weaker than bonds formed.
(c)Bonds broken are of equal strength to bonds formed
(d)Hreaction value has nothing to do with bond energies.
4-
What equation must be used to represent the formation of nitric acid,
HNO3(ℓ), when we want to include its value of Hfo HNO3(ℓ) = -173.2
kJ mol-1?
(a) H2(g) + N2(g) + 3 O2(g)  2HNO3(ℓ);
Hfo = -346.4 kJ mol-1
(b)1/3H2(g) + 1/3N2(g) + O2(g)  2HNO3(ℓ); Hfo = -115.5 kJ mol-1
(c)1/2H2(g) +1/2N2(g) +3/2O2(g) HNO3(ℓ); Hfo =-173.2 kJ mol-1
(d)NO2(g) + H2O(ℓ)  4HNO3(ℓ) + 1/2H2(g) Hfo =-173.2 kJ mol-1
5-
Which of the following expressions is incorrect:
(a) E = qv
(b)E = q - PV (if the only work available is of expansion)
(c)E= H +PV
(d)H =qp
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6-
7-
Given the following data:
H2(g) + O2(g)  H2O2(ℓ);
Ho = - 188 kJ
H2(g) + ½O2(g)  H2O(ℓ),
Ho = - 286.4 kJ
The standard enthalpy ∆Ho for the following reaction in kJ will be:
H2O2(ℓ)  H2O(ℓ) + ½O2(g),
Ho = ?
(a)-98
(b)-628
(c)+176
One of the following relationships is incorrect:
(d)+118.4
(a)E = H- (PV)
(b)E = H -  (nRT) assume ideal gas
(c)E = qp + PV (at constant pressure)
(d) H= qp
8-
Given:
C2H6 (g) + 7/2O2 (g)  2CO2 (g) + 3H2O (ℓ); Ho = -1460 kJ
[Hf0 (CO2) = -393.7 kJ; Hf0 (H2O) = -285.6 kJ ] then Hfo (C2H6) in
kJ/mol equals:
(a)+184.2
9-
(b) -780.7
(d)-184.2
If the heat evolved by the combustion of 3.00 gms of glucose,
C6H12O6(s) in a bomb calorimeter (constant volume) is 47.0 kJ. Then
for one mole of glucose, the quantity of heat evolved (in kJ) is
(according to the equation):
C6H12O6 (s) + 6O2 (g)  6CO2 (g) + 6H2O (ℓ); H = ?
(a) 2.82x103
10-
(c)+780.7
(b)2.22x102
(c) 6.15x103
Given the following thermochemical equations
1)
C (graphite) + O2 (g)  CO2 (g)
2)
S (rhombic) + O2 (g)  SO2 (g)
3)
CS2 (ℓ) + 3O2 (g)  CO2 (g) + 2SO2 (g)
Calculate Hfo of CS2 (ℓ)
(a)86 kJ mol-1
(b)- 86 kJ mol-1
(c)- 382.25 kJ mol-1
72
(d)1.95x104
Ho =- 393.5 kJ
Ho=-296.25 kJ
H =- 1072 kJ
(d)207.5 kJ mol-1
11- Under conditions of constant volume, the heat changes that occurs during
a chemical reaction is equal to:
(a)H
(b)T
(c)W
73
(d)E