Chemistry - Unit %

Practice Practice Practice !!!

Properties of Gases (2)

1. Take the shape and volume of the container they are in

2. Easily compressed because of weak attractive forces, causing them to be spaced out

What does the Brownian Motion state?

Microscopic particles move randomly in gases and liquids.

What does the Kinetic Molecular Theory state?

All substances are made of entities that are in constant and random motion.

What are the 5 assumptions about ideal gases that the Kinetic Molecular Theory of Gases states?

1. Gas molecules are small compared to the volume of the container they are in; therefore, they are far apart. This makes them easily compressible.

2. Neither attractive nor repulsive forces exist between gas molecules.

3. They have high translational energy (particles travelling in a straight line)

4. When gas particles collide, they bounce off each other, and no kinetic energy is lost.

5. Kinetic energy of gas molecules increases as the temperature and mass increase. Decreases as pressure increases, vice versa.

How does the size of the force applied affect pressure?

The greater the force, the greater the pressure.

What is kinetic energy?

The energy possessed by a moving object.

How does temperature affect kinetic energy?

Hotter temperatures increase kinetic energy, allowing substances to change states. Colder temperatures decrease kinetic energy, also allowing substances to change states.

What is temperature in relation to kinetic energy (what does it measure)?

The measure of average kinetic energy in the entities of a substance.

What is translational motion?

Particles travelling in a straight line.

What is rotational motion?

Spinning motion of particles around other particles.

What is vibrational motion?

The back and forth motion of particles in a fixed position.

What does the type of motion of particles depend on?

Strength of attractive forces.

What is the formula for pressure?

P = F/A

When is pressure created by gases?

When the moving gas particles collide with the surface of the container holding them.

What is atmospheric pressure?

Pressure exerted by air on objects.

What is Standard Atmospheric Pressure?

The pressure exerted by a column of air with a base of one square metre.

What is Standard Atmospheric Pressure equal to?

101.3 kpa

What does STP stand for?

Standard temperature and pressure.

What is the temperature and pressure at STP (standard temperature and pressure)?

Temperature = 0 degrees Celsius

Pressure = 101.325 kPa

What is SATP?

Standard Ambient Temperature and Pressure

What is the temperature and pressure at SATP (standard ambient temperature and pressure)?

Temperature = 25 degrees Celcius

Pressure = 100 kPa

How does altitude affect atmospheric pressure?

The density of gases decreases as the altitude increases.

Lower altitude = higher density, higher pressure

Higher altitude = lower density, lower pressure

What is absolute zero? (Defintion)

The temperature at which a gas theoretically has no volume.

What is the value of absolute zero?

-273.15 degrees Celcius, aka 0k.

The freezing point of water is 0 degrees Celcius, what is the equivalent value in kelvin?

273.15k

The boiling point of water is 100 degrees Celcius, what is the equivalent value in kelvin?

373.15k

What is the formula for converting Celsius to Kelvin?

T = t + 273.15

What is the formula for converting Kelvin to Celcius?

t = T - 273.15

What does the law of proportionality state?

If ‘a’ if proportional to ‘b’

Then a = kb

Explain the law of proportionality.

‘a’ increases and decreases at the same rate as ‘b’. Since b is smaller, we introduce a constant ‘k’ to make them equivalent as they increase/decrease.