NAME ______________________________________________ PER _____ CE CHEM CH 6 REVIEW
SHOW ALL WORK ON YOUR OWN PAPER.
1. A gas sample is collected in a balloon. What happens to the density of the gas sample as the sample is
cooled? Heated? Explain why. As a gas is cooled it condenses, making the volume lower. Density is
mass divided by volume, therefore the density increases as the gas is cooled.
As the gas is heated the volume increases and therefore density decreases (you would be dividing by
a larger number).
2. What does potential energy resulting from the attraction of particles, do to the separation distances?
(this question is not worded well, sorry) Potential energy resulting from the attraction of particles
increases when separation distance increases.
3. Describe the difference between Cohesive forces and distruptive forces in matter and what kind of
energy they are related to. Cohesive force is the attractive force between particles associated with
potential energy. Distruptive force results from particle motion, therefore associated with kinetic
energy.
4. High density is characteristic of which states of matter? Solid & liquids
5. Definite shape is a characteristic of which state of matter? Solid
6. Small compressibility is a characteristic of which state of matter? Solids & liquids
7. You have a patient that is currently experience extreme discomfort after eating a large quantity of
beans. The pain is being caused by the build up of gas pressure in the large intestines. If you were able
to put a pressure gauge in to the patient, which of the following would be a reasonable pressure that
you might observe. (not really addressed in class or the book, but on the test!)
a.
8.
9.
10.
11.
860 torr
b.
860 psi
c.
860 pascal
d.
860 atm
A pressure is recorded as 922 torr. What is this pressure in atm? 𝟗𝟐𝟐 ÷ 𝟕𝟔𝟎 = 𝟏. 𝟐𝟏 𝒂𝒕𝒎
Convert a temperature of 85℃ into Kelvin. 𝟖𝟓 + 𝟐𝟕𝟑 = 𝟑𝟓𝟖 𝑲
Convert a temperature of 10 K into Celsius degrees. 𝟏𝟎 − 𝟐𝟕𝟑 = −𝟐𝟔𝟑℃
Which of the following pressure units is largest? Explain your answer. 1 torr = 1/760 atm, 1 mmHg =
1/760 atm, 1psi = 1/14.7 atm, all are smaller than 1 atmosphere
a.
one torr
b.
one mm Hg
c.
one psi
d.
one atm
12. Increasing the pressure on a gas at constant temperature does what to the volume of the gas?
Decreases the volume of gas (PV=P2V2)
13. 2500 liters of oxygen gas is produced at 1.00 atm of pressure. It is to be compressed and stored in a
20.0 liter cylinder. If temperature is constant, calculate the pressure of the oxygen in the cylinder.
𝟐𝟓𝟎𝟎(𝟏. 𝟎𝟎) = 𝟐𝟎. 𝟎𝑷𝟐 solve for P2= 125 atm
14. A balloon has a volume of 3.00 liters of 32°C and 1.00 atmosphere of pressure. What will be the
balloon's volume in liters if the pressure is increased to 3.00 atmospheres at 32°C?
𝟏. 𝟎𝟎 × 𝟑. 𝟎𝟎 = 𝟑. 𝟎𝟎𝑽 (temp. didn’t change, solve for V) V = 1.00L
15. A gas sample has a volume of 500 mL at 40°C. At what Celsius temperature would the gas have a
.𝟓𝟎𝟎𝑳
.𝟐𝟓𝟎𝑳
volume half as large? 𝟑𝟏𝟑𝑲 = 𝑻
cross multiply, then solve. .500T=78.25; T= 156.5K The question
asks for ℃ 156.5K – 273 = 116.5℃
16. A 1.2 liter sample of gas is at 35°C and 1.0 atmosphere of pressure. If the temperature decreases to 20°C
and the pressure decreases to 0.60 atmospheres, what is the new volume in liters?
𝟏.𝟎(𝟏.𝟐)
.𝟔𝟎𝑽
= 𝟐𝟗𝟑 cross multiply and solve V = 1.9L
17. A sample of gas collected at 23.0°C and a pressure of 640 torr has a volume of 1.83 liters. What volume
𝟑𝟎𝟖
in liters will the gas occupy at 38.0°C under a pressure of 501 torr?
𝟔𝟒𝟎
)(𝟏.𝟖𝟑)
𝟕𝟔𝟎
(
𝟐𝟗𝟔
=
(
𝟓𝟎𝟏
)𝑽
𝟕𝟔𝟎
𝟑𝟏𝟏
2.5L
18. A 12.00 liter gas sample is collected at a temperature and pressure of 27.0°C and 1.20 atm. It is desired
to transfer the gas to a 3.00 liter container at a pressure of 1.00 atm. What must be the temperature of
𝟏.𝟐𝟎(𝟏𝟐.𝟎𝟎)
𝟏.𝟎𝟎(𝟑.𝟎𝟎)
the gas in the 3.00 liter container? 𝟑𝟎𝟎𝑲 =
T = 62.5K or -210.5℃
𝑻
19. A gas sample collected at 35.0°C and a pressure of 710 torr has a volume of 200 mL. The temperature
and pressure are changed, and the gas is compressed to 150 mL. The new temperature is 50.0℃; what
𝟕𝟏𝟎(.𝟐𝟎𝟎)
𝑷.𝟏𝟓𝟎
is the new pressure? 𝟑𝟎𝟖𝑲 = 𝟑𝟐𝟑 P = 993 torr
20. Calculate the volume in liters of 2.50 moles of gas at STP. 2.50moles(22.4L/moles) = 56.0 L
21. What pressure will 5.20 mol of N2 gas exert if confined in a 15.0 L container at 100°C?
𝑷(𝟏𝟓. 𝟎) = 𝟓. 𝟐𝟎(𝟎. 𝟎𝟖𝟐𝟏)𝟑𝟕𝟑 P = 10.6 atm
22. What volume in liters is occupied by 10.22 g of SO2 gas confined at a pressure of 1200 torr at 75.0°C?
𝑷𝑽 = 𝒏𝑹𝑻 change P to atm, T to atm and g to moles P=1200/760 = 1.58 atm T = 75.0 + 273=348
g=10.22/64.0 = .160 moles. Plug in the numbers and solve. V =2.89L
23. What volume of ammonia gas, NH3, in liters is produced at STP by the complete reaction of 100 g of
nitrogen, N2, with excess hydrogen? N2 + 3H2 → 2NH3 Change 100g N2 to moles 100/28 = 3.57 moles N2
𝟏 𝒎𝒐𝒍𝒆 𝑵
𝟐 𝒎𝒐𝒍𝒆 𝑵𝑯
Now compare moles in balanced equation. 𝟑.𝟓𝟕 𝒎𝒐𝒍𝒆 𝑵𝟐 = 𝒙 𝒎𝒐𝒍𝒆 𝑵𝑯𝟑
𝟐
𝟑
Solve for moles ammonia. 7.14 moles NH3 multiply by 22.4L/1 mole. 160L NH3
24. A mixture of helium, argon and krypton is made and stored in a cylinder at a total pressure of 2.30 atm.
The partial pressure of helium is 800 torr, and that of argon is 250 torr. What is the partial pressure of
𝟖𝟎𝟎
𝟐𝟓𝟎
krypton in the mixture? 𝟐. 𝟑𝟎 = 𝟕𝟔𝟎 𝒂𝒕𝒎 + 𝟕𝟔𝟎 𝒂𝒕𝒎 + 𝑷𝑲𝒓 solve for partial pressure of Kr. .92 atm
25. What is the total pressure of a gaseous mixture that contains three gases with partial pressures of
0.845 atm, 320 torr and 310 mm Hg? Convert all to the same units, then add.
.421 + .408 + .845 = 1.67 atm
26. Which of the following gases would diffuse about one-third as fast as helium gas, He? Justify your
answer a. HCl b. NH3 c. CH4 d. H2O
𝒓𝒂𝒕𝒆 ?
𝒎𝒐𝒍𝒂𝒓 𝒎𝒂𝒔𝒔 𝑯𝒆
Use the equation 𝒓𝒂𝒕𝒆 𝑯𝒆 = √
𝒎𝒐𝒍𝒂𝒓 𝒎𝒂𝒔𝒔 ?
𝟏
𝟒
= √𝒎𝒐𝒍𝒂𝒓 𝒎𝒂𝒔𝒔 ? solve, square both sides then cross
𝟑
multiply molar mass = 36 HCl is the closest at 35.5g/mol
27. Which of the following pairs of gases would diffuse at essentially the same rate? Justify your answer
a. NO2 and NO b. O2 and Ar c. PH3 and C2H2
D. N2O and CO2
The gases will need to be about the same molar masses.
28. In which phase change does the energy of the water increase? Melting, Evaporating
29. Which phase changes would be an exothermic process? Freezing, deposition, condensation
30. The temperature of a liquid is decreased. What happens to the vapor pressure of the liquid as a result?
Vapor Pressure would decrease
31. What can influence the vapor pressure of liquids? Polarity of particles, temperature
32. When a liquid sample is taken from sea level to a higher elevation, what happens to the external
(atmospheric) pressure on the liquid and the boiling point of the liquid? Both decrease
33. The vapor pressure of a liquid
a. decreases with increasing temperature. c. is equal to one atmosphere at the normal boiling point
b. is independent of temperature.
d. cannot be measured.
34. Ethylene dichloride is an effective cooling agent when allowed to evaporate. The heat of vaporization
is 85.3 calories per gram. How much heat could be removed from the skin if 2.70 grams of ethylene
dichloride were sprayed on and allowed to evaporate? 2.70g x (85.3 cal/g) = 230.3 calories
35. The heat of fusion for zinc chloride is 40.4 calories per gram at the melting point of 275°C. How much
heat is required to melt 500 g of zinc chloride at its melting point? 40.4cal/g x (500g) = 20,200 calories
36. The specific heat of ice is 0.48 cal/g°C. How much heat will it take to raise the temperature of 12 g of ice
from -30°C to -20°C? heat = 12g(.48 cal/g°C)(-20- -30) = 57.6 cal
37. In terms of boiling point, what is the effect of moving water to a point 1500 meters higher than the
starting point? The boiling point decreases
38. The force resulting from particle motion is referred to as disruptive forces.
39. Arrange the physical states of matter (gas - g, solid - s, liquid - l) in order of increasing energy of the
particles (lowest to highest)? S < l < g
40. Overtime, a latex balloon will lose its shape and buoyancy. Which process can be used to explain why
this occurs? Effusion-balloons have pores and the gas can escape through the small holes.