Gas Temperature and Pressure - SP14d

Gas Temperature and Pressure - SP14d

What do you already know - write as many facts as you can on the next three or four slides

Open Ended

What do you already know about gas pressure? (Don't press enter until you have finished all your answer)

Open Ended

Describe the motion, arrangement and forces of attraction of the particles in a gas. (Don't press enter until you are happy with your answer)

Open Ended

What is the temperature of a gas dependent on?

Open Ended

If you remembered anything else you wanted to add.

The relationship between gas pressure, temperature and particle kinetic energy.

• Explain gas pressure in terms of collisions of gas particles with container walls

• Explain how gas pressure changes with temperature

• Describe the relationship between kelvin temperature and average kinetic energy

• Define absolute zero, and convert between Celcius and Kelvin

Gases and Gas Temperature

• The particles in a gas are spread out and move fast in random directions, colliding with each other and the container.

• The temperature of the gas is a measure of the average kinetic energy of the particles.

• The more the kinetic energy of the particles the hotter the gas

Gas Pressure

• Gas pressure is caused by the particles colliding with the surface of the container walls.

• The faster and more collisions per second on the walls the greater the force exerted, so the greater the pressure.

• What changes might increase gas pressure and why?

Gas Pressure

• The greater the temperature, the faster the molecules will move, so the more frequent the collisions and the greater the force.

• The smaller the volume, the more frequent the collisions so the greater force per area.

• Adding more particles will also increase the number of collisions.

Gas Pressure

• Gas pressure is measured in Pascals (Pa).

• 1 Pa = 1 N/m² - Why is this true?

• Pressure = Force / Area

Multiple Choice

Pressure is

• defined as the mass that an object exerts when at rest.

• defined as the number of moles of substance divided by the mass of the substance.

• created by the force of the gas particles impacting the walls of the container.

Multiple Choice

The reason gases can be compressed is because:

• The particles are very close together.

• The particles are merely vibrating.

• The particles are unable to move.

• The particles are very far apart.

Multiple Choice

Which of these is under greater pressure?

Multiple Choice

The pressure inside the syringe will decrease if we move the plunger in:

• Direction A

• Direction B

• We don't have to move the plunger as the pressure will change on its own.

• None of the above answers.

Multiple Choice

The pressure inside the balloon will:

• Decrease

• Increase

• Remain the same

Multiple Choice

Which of the following would increase the (gas) pressure of a system?

• Increase the Temperature
• Pump in more gas
• Decrease the volume
• All of these

Multiple Choice

If a hairspray can is heated, what can be expected of the pressure of the gas inside the can?

• The pressure will increase

• The pressure will decrease

• The pressure will remain constant

Multiple Choice

The pressure of the gas in the balloon in the ice water will be:

• Greater than that of the balloon in the boiling water.

• Less than that of the balloon in the boiling water.

• The same as that of the balloon in the boiling water.

Open Ended

The answer to the last question might have shocked you. Try to explain the answer

Gas Temperature

• If we keep the mass of and the volume of the gas constant e.g in a glass flask, and heat it, the pressure in the flask will steadily rise

• We can say that for a fixed mass and fixed volume of gas, gas pressure is directly proportional to the temperature

• What do you notice about this graph?

Gas Temperature

• When the graph line is extended back the gas shows zero pressure at -273^oC. This is the same for all gases.

• At this temperature the particles would stop moving completely.

• This temperature is called absolute zero

Gas Temperature

• The Kelvin temperature scale, measures temperature relative to absolute zero.

• 1 K is on the kelvin scale has the same interval as 1 ^oC

• K = ^oC - 273

• ^oC = K + 273

• The average kinetic energy of a gas is directly proportional to the kelvin temperature of the gas.

Multiple Choice

Convert

 $0\ K$  to Celsius

•  $273^oC$  

•  $-273^oC$  

•  $32^oC$  

•  $-32^oC$  

Multiple Choice

Convert

 $0^oC$  to Kelvin

•  $-273\ K$  

•  $273\ K$  

•  $32\ K$  

•  $-32\ K$  

Multiple Choice

What is the boiling point of water on the Celsius scale?

•  $0^oC$ 

•  $373^oC$ 

•  $100^oC$ 

•  $212^oC$ 

Multiple Choice

What is the boiling point of water on the Kelvin scale?

•  $0^{ }K$ 

•  $373^{ }K$ 

•  $100^{ }K$ 

•  $212^{ }K$ 

Multiple Choice

Convert

 $300\ K$  to Celsius

•  $573^oC$  

•  $37^oC$  

•  $27^oC$  

•  $600^oC$  

Multiple Choice

Convert

 $100^oC$  to Kelvin

•  $373\ K$  

•  $273\ K$  

•  $212\ K$  

•  $0\ K$  

Multiple Choice

Convert

 $450\ K$  to Celsius

•  $723^oC$  

•  $277^oC$  

•  $177\ ^oC$  

•  $623^oC$  

Fill in the Blank

At absolute zero the kinetic energy of the particles is ............ joules.

Multiple Choice

The average kinetic energy of the particles in a gas is directly ................. to the ................ temperature of the gas.

• proportional

  kelvin

• proportional

  natural

• related

  natural

Multiple Choice

For a fixed ......... of gas in a fixed ................. the gas pressure ................... as the temperature increases.

• container

  temperature

  decreases

• mass

  volume

  decreases

• mass

  volume

  increases

Multiple Choice

As the temperature increases the particles gain ................. energy, so collide with the container walls more .................. and with a greater ................ This increases ............. pressure. (which word is NOT needed)

• gas

• kinetic

• temperature

• frequently

• force

Open Ended

Extension question - Explain using key words - why gas pressure increasing with rising temperature and why it is zero at absolute zero.