Ideal Gases
What is the volume of 0.414 mol of an ideal gas at 1.21 atm pressure and 30°C?
8.51 liters
Name three (3) assumptions of the kinetic-molecular theory of gases.
1) Gases consist of a large number of molecules in constant random motion
2) Volume of individual molecules negligible compared to volume of container
3) Intermolecular forces (forces between gas molecules) negligible
4) As kinetic energy increases, the velocity of the gas molecules increases
5) Root mean square speed, u, is the speed of a gas molecule having average kinetic energy
Which intermolecular force results from the formation of an instantaneous dipole?
London dispersion force
Sublimation is the change of phase from _____ to _____ form.
Solid to gas
A 2.39L tank an ideal gas at 1 atm pressure. If the gas is quickly transferred to a 1.8 L tank, what is the new pressure?
0.75 atm
Slideshow: Which line corresponds to the gas at the highest temperature and why?
E
Trifluoromethane (CHF3) has a higher boiling point than tetrafluoromethane (CF4) primarily due to _____.
The presence of hydrogen bonding
The point at which the vapor pressure of a liquid is equal to the atmospheric pressure is known as the _____ point of the substance.
Boiling point or condensing point
A gas at 298K and 681 torr occupies a volume of 345 mL. What is the volume of this gas at 273K and 760 torr pressure?
283 mL
What is the root mean square speed of NO molecules at 400.0K?
575.7 m/s
Which of the following molecules can exhibit dipole-dipole interactions?
CO2, H2, PF5, SF4
SF4 (polarity)
Water can be made to boil at 110°C instead of 100°C by ______.
Increasing the external pressure
Consider the reaction:
2 NaHCO3 (s) → Na2CO3 (s) + H2O (l) + CO2 (g)
If 10.64g of NaHCO3 decomposes, what is the volume of carbon dioxide produced at STP conditions?
2.19 L of CO2
What is the molar mass of an unknown gas if it effuses 1.3 times faster than propane, C3H8 (MM = 44.092 g/mol)?
26 g/mol
Arrange in order of increasing boiling point:
HF, CO2, NaCl, Kr, H2O
Kr < CO2 < HF < H2O < NaCl
Cyclohexane (C6H12) has a higher vapor pressure than water at 100°C. Therefore, the boiling point of cyclohexane is ______ that of water.
Lower
An empty balloon weighs 38.446 g. After it is filled with 62.1 mL of an unknown diatomic gas, it weighs 38.621 g. If the atmospheric pressure is 750 mmHg and the temperature is 24.3°C, what is the identity of the gas?
Cl2
According to the kinetic-molecular theory, if a gas's temperature is raised from 100°C to 200°C, its average kinetic energy will (increase/decrease) by a factor of _____.
Increase, 1.27
Examine the boiling points. Which effect causes this trend?
HCl (b.p. = –85°C)
HBr (b.p. = –67°C)
HI (b.p. = –35°C)
An increase in the polarizability of the molecule going from HCl to HI (molar mass increases)
Arrange the molecules in order of increasing vapor pressure (at the same temperature)
NH3, I2, HF, CH4
HF, NH3, I2, CH4