Cooling by Evaporation

Question 1

What is the difference between boiling and evaporation?

Answer 1

Boiling -
1. H2O vapour
2. Happens at boiling point (100 degrees celsius)
3. Happens throughout the liquid

Evaporation -
1. Heating the liquid
2. Can happen at any temp.
3. Happens on the surface

Question 2

Explain the process of evaporation

Answer 2

1. molecules in a liquid have a lot of intermolecular space, with strong intermolecular bonds.
2. The particles at the surface are free (have less bonds)
3. They take kinetic energy from the particles below, break their bonds and are released into the air in the form of H2O vapour.
4. Said process can be sped up by radiation
5. The particles below have less KE and less temp.

Question 3

What are electromagnetic waves?

Answer 3

1. Electromagnetic waves are energy waves
2. They don’t need particles to move from one place to another
3. Can move through vacuum

Question 4

What are the factors affecting evaporation? How do they affect evaporation?

Answer 4

1. Temperature - D.P
   More temperature = more K.E = more likely for liquid to be able to break away and become a gas
2. Wind Speed - D.P
3. Surface Area - D.P
   More area exposed to air, allowing water molecules to acquire more heat energy from the surroundings
4. Humidity - I.P
   There is already a lot of water vapour in the air (it is humid) and so there is less space for water vapour from the evaporated molecules

Humidity - air saturated with H2O vapour

Question 5

Define Newton’s Law of Cooling

Answer 5

According to Newton’s Law of Cooling, the rate of loss of heat from a body is directly proportional to the difference in the temperature of the body and its surroundings.