Kinetic Molecular Theory (KMT)
Ideal vs. Real Gases
Gas Laws in Action
Vapor Pressure & Boiling
Avogadro & STP
100
According to KMT, how do gas particles move?
In random, constant, straight-line motion.
100
Under what conditions do real gases behave most like ideal gases?
High temperature and low pressure.
100
A gas at 2.0 L and 1.0 atm is compressed to 0.5 L. What’s the new pressure? State the Gas Law.
4.0 atm (Boyle's Law)
100
The boiling point of a pure substance is defined as
the temperature at which vapor pressure...
The vapor pressure equals the external
pressure
100
What are the STP conditions?
273 K (0°C) and 1 atm (101.3 kPa).
200
According to KMT, how is average kinetic energy related to temperature?
Average kinetic energy is directly proportional to temperature in kelvin.
200
Why do real gases deviate from ideal behavior?
They have volume and intermolecular attractions.
200
What is the combined gas law? Describe the combined gas law and when it’s used.
Used when pressure, volume, and temperature all change.
200
As the temperature of a liquid increases, its vapor
pressure
As temperature increases, vapor pressure increases.
200
What does Avogadro’s Hypothesis state?
Equal volumes of gases at the same temperature and pressure contain equal numbers of molecules.
300
What causes gas pressure in a container?
Collisions of gas particles with the container walls.
300
Which gas behaves most ideally: Ar, H₂, or NH₃?
Ar (small and weak IMF).
300
What is the relationship between temperature and volume? What is the law? Sketch a graph.
Direct
Charle's Law
300
How do intermolecular forces affect vapor pressure?
Stronger IMF → lower vapor pressure.
300
1 mole of any gas occupies how many liters at STP?
22.4 L.
400
What assumption of KMT is not true for real gases?
Gas particles have no volume and no intermolecular forces.
400
When do gases behave least like ideal gases?
Low temperature and high pressure.
400
A gas has an initial pressure of 2.0 atm, an initial volume of 5.0 L, and a temperature of 300 K. If the temperature is increased to 600 K while the volume remains constant, what will be the final pressure?
4.0 atm
400
What is the vapor pressure of water at 75°C?
38 kPa
400
Three 1 L samples of CO₂, He, and O₂ are at 298 K and 101.3 kPa. Which has the most molecules?
They all have the same number of molecules.
500
Explain why a heated aerosol can may explode, using KMT.
Higher temperature → particles move faster → more collisions → increased pressure → can explodes.
500
Explain why O₂ deviates more from ideal behavior than Kr.
O₂ has larger molecules and stronger intermolecular forces.
500
A pressure cooker contains 1.5 L of steam at a pressure of 2.0 atm and a temperature of 400 K. If the temperature and pressure of the steam decreases to STP what is the new volume ?
2.05 L
500
Which liquid will evaporate more rapidly? Explain your answer in terms of intermolecular forces.
The higher vapor pressure of liquid A indicates that the intermolecular forces between its molecules are weaker, allowing the molecules to escape more readily to the vapor phase.
500
A weather balloon has a volume of 52.5 liters at a temperature of 295 K. The balloon is released and rises to an altitude where the temperature is 252 K.
What pressure, in atmospheres (atm), is equal to 45.6 kPa?
.45 or 0.45 atm