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Chapter 8: Gases, Solids Liquids
1. What is the transformation from one substance to another
called?
6. The pressure of gas in a 600.0 mL cylinder is 65.0 mmHg. To
what volume must it be compressed to increase the pressure to
385 mmHg?
A phase change
2. T/F: during sublimation, a solid changes directly to a gas.
3.
Which of the following is not a characteristic of an ideal gas?
a.
As the temperature increases, the kinetic energy of the gas
particles increases.
b. The area of the gas is smaller than the area of the container.
c. The total kinetic energy of the particles is not constant
The total kinetic energy of particle is constant. The
collisions within the container are elastic.
d. Gases can mix together easily due to their random motion and
no attractive forces.
4. Convert the following values into mmHg
a. standard pressure
1 𝑎𝑡𝑚 = 𝟕𝟔𝟎𝒎𝒎𝑯𝒈
b. 25.3 psi
1 𝑎𝑡𝑚
760 𝑚𝑚𝐻𝑔
25.3 𝑝𝑠𝑖 ×
×
= 𝟏. 𝟑𝟏 × 𝒙𝟏𝟎𝟑 𝒎𝒎𝑯𝒈
14.7 𝑝𝑠𝑖
1 𝑎𝑡𝑚
c. 7.5 atm
760 𝑚𝑚𝐻𝑔
7.5 𝑎𝑡𝑚 ×
= 𝟓. 𝟕𝒙𝟏𝟎𝟑 𝒎𝒎𝑯𝒈
1 𝑎𝑡𝑚
d. 28.0 in. Hg
2.54 𝑐𝑚
1 𝑚 1000 𝑚𝑚
28.0 𝑖𝑛 𝐻𝑔 ×
×
= 𝟕𝟏𝟏. 𝟐 𝒎𝒎𝑯𝒈
1 𝑖𝑛𝑐ℎ
100 𝑐𝑚 1 𝑚
e. 41.8 Pa
1 𝑎𝑡𝑚
760 𝑚𝑚𝐻𝑔
41.8 𝑃𝑎 ×
×
= 𝟑. 𝟏𝟒𝒙𝟏𝟎−𝟏 𝒎𝒎𝑯𝒈
101,325 𝑃𝑎
1 𝑎𝑡𝑚
5. What is Boyle’s law? What happens to the Volume as the
pressure increases?
a. Boyles Law states that as Volume decreases Pressure
increases
𝑃1𝑉1 = 𝑃2𝑉2 (𝑒𝑞𝑢𝑎𝑡𝑖𝑜𝑛 𝑏𝑒𝑖𝑛𝑔 𝑢𝑠𝑒𝑑 𝑓𝑟𝑜𝑚 𝐵𝑜𝑦𝑙𝑒 ′ 𝑠 𝐿𝑎𝑤)
Be consistent with units.
(65.0)(600) = (385)(𝑉2)
39000 385𝑉
=
385
385
𝑽 = 𝟏𝟎𝟏 𝒎𝑳
7. T/F: The principles behind Charles Law theorize that as the
Volume decreases the Kelvin Temperature decreases.
8. A hot air balloon has a volume of 960 L at 18°C. To what
temperature must it be heated to raise its volume to 1200L,
assuming pressure remains constant?
𝑽𝟏 𝑽𝟐
=
𝑻𝟏 𝑻𝟐
Temperature must be in Kelvin.
18𝐶 + 273.15𝐾 = 291.15𝐾
960
1200
=
291.15
𝑇2
349380 = 960𝑇2
𝑻𝟐 = 𝟑𝟔𝟒𝑲 𝒐𝒓 𝟗𝟏℃
9. A glass laboratory flask is filled with gas at 25°C and 0.95 atm
pressure, sealed, and then heated to 117°C. What is the
pressure inside the flask? What can you conclude about GayLussac’s law?
25℃ + 273.15𝐾 = 298.15
117℃ + 273.15 = 390.15
𝑷𝟏 𝑷𝟐
=
𝑻𝟏 𝑻𝟐
0.95
𝑃2
=
298.15 390.15
𝑷𝟐 = 𝟏. 𝟐 𝒂𝒕𝒎
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Chapter 8: Gases, Solids Liquids
10. When H2 gas was released by the reaction of HCl with Zn, the
volume of H2 collected was 75.4 ml at 23°C and 748 mmHg.
What is the volume of the H2 at 0°C and 1.00 atm pressure
(STP)?
𝑷𝟏𝑽𝟏 𝑷𝟐𝑽𝟐
=
𝑻𝟏
𝑻𝟐
Step 1: Convert to correct units:
0℃ + 273.15𝐾 = 273.15𝐾
23℃ + 273.15𝐾 = 296.15𝐾
1 𝑎𝑡𝑚
748𝑚𝑚𝐻𝑔 ×
= 0.98 𝑎𝑡𝑚
760 𝑚𝑚𝐻𝑔
Step 2: Place in known values and cross multiple to solve for
unknown V2:
(0.98)(75.4) (1 .0)(𝑉2)
=
(296.15)
273.15
𝑉
0.2495 =
273.15
𝑽 = 𝟔𝟖 𝒎𝒍
11. How many liters does 1 mol of gas occupy at STP?
𝟐𝟐. 𝟒 𝑳𝒊𝒕𝒆𝒓𝒔
1 𝑚𝑜𝑙𝑒
12. If 15.0 g of CO2 has a volume of 0.30 L at 310K, what is its
pressure in mmHg?
PV=nRT
R=0.0821 (constant)
1 𝑚𝑜𝑙𝑒 𝑜𝑓 𝐶𝑂2
15.0 𝑔𝑟𝑎𝑚𝑠 ×
= 0.34 𝑚𝑜𝑙𝑒𝑠 𝑜𝑓 𝐶𝑂2
44.01 𝑔𝑟𝑎𝑚𝑠 𝑜𝑓 𝐶𝑂2
= # 𝑓𝑜𝑟 𝑛
(𝑝)(0.30) = (0.34)(0.0821)(310)
760 𝑚𝑚𝐻𝑔
𝑃 = 28.84 𝑎𝑡𝑚 ×
= 𝟐. 𝟐 × 𝟏𝟎𝟒 𝒎𝒎𝑯𝒈
1 𝑎𝑡𝑚
13. If the partial pressure of oxygen in the air at 1.0 atm is
160mmHg, what is the partial pressure on the summit of Mt.
Whitney, where the atmospheric pressure is 440 mmHg?
Assume that the percent oxygen is the same.
1 𝑎𝑡𝑚
160 𝑚𝑚𝐻𝑔 (𝑃𝑃)
=
= 𝟗𝟑 𝒎𝒎𝑯𝒈
0.58 𝑎𝑡𝑚 (𝑃𝑃 𝑜𝑛 𝑀𝑡. 𝑊ℎ𝑖𝑡𝑛𝑒𝑦)
440 𝑚𝑚𝐻𝑔 𝑥
1 𝑎𝑡𝑚
= 0.58 𝑎𝑡𝑚 (𝑝𝑙𝑢𝑔 𝑖𝑛𝑡𝑜 𝑒𝑞𝑢𝑎𝑡𝑖𝑜𝑛)
760 𝑚𝑚𝐻𝑔
14. If I place 3 moles of N2 and 4 moles of O2 in a 35 L container at a
temperature of 250 C, what will the pressure of the resulting
mixture of gases be?
pv = nrt
Using the ideal gas law, you can determine that the partial
pressure of nitrogen in this mixture will be 2.09 atm (211.8 kPa)
and the partial pressure of oxygen will be 2.79 atm (282.7 kPa).
When you add these together, the total pressure in the
container is 4.88 atm (494.5 kPa).
15. What are the only atoms that can bond with hydrogen to form a
hydrogen bond? What type of charge is present within the
molecule?
Hydrogen atoms will bond with F,N,O.
16. List the intermolecular forces in order of increasing strength
Hydrogen Bonds > Dipole-dipole> London Dispersion
17. Draw the following structures (A-C). Identify what type of
intermolecular force is present.
a.
b.
c.
d.
N2 dispersion
HCN dispersion, Dipole-dipole
CH3CO2H dispersion, Dipole-dipole, Hydrogen Bonds
MgBr2 London Dispersion
18. Dimethyl ether (CH3OCH3) and ethanol (C2H5OH) have the same
formula (C2H6O), but the boiling point of dimethyl ether is -25°C
while ethanol is 78°C. Explain.
Dimethyl Ether does not have a hydrogen bond it has an CH3-OCH3 structure. Ethanol is an alcohol and has an O-H bond,
which is a hydrogen bond. Hydrogen Bonds have high melting
point and high boiling points because the bond will require
higher temperatures to break or phase change.
Chapter 8: Gases, Solids Liquids
19. What is the difference between amorphous and crystalline solid?
An amorphous solid is a solid whose particles do not have an
orderly arrangement whereas a crystalline solid is a solid
whose atoms, ions, and molecules are held together in an
orderly fashion. Crystalline solids can be further characterized
as ionic, molecular, covalent, or metallic
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