Condensation and Evaporation
Explain the process of condensation.
1. the gas cools and the particles in the gas slow down, losing kinetic energy, 2. the attractive forces between the particles pull them closer together 3. if the temperature gets cold enough and the gas particles get close enough together, condensation can take place and so cause the gas to turn into a liquid
Explain evaporation.
evaporation is when particles escape from a liquid
When can particles near the surface of a liquid escape and become a gas?
if the particles are travelling in the right direction to escape the liquid, if the particles are travelling fast enough - they have enough kinetic energy to overcome the attractive forces of the other particles in the liquid
What causes the rate of evaporation be quicker?
if the temperature is higher, if the density is lower, if the surface area is larger and if the airflow over the liquid is greater
What causes the rate of condensation to be quicker?
if the temperature of the gas is lower, if the temperature of the surface that the gas touches is lower, if the density is higher and also if the airflow is less
What happens to water vapour in the air when it comes into contact with a cold surface?
it condenses
What is the steam rising from something like a kettle?
it is invisible water vapour that is condensing to form tiny water droplets as it spreads into cooler air
What is condensation?
it is when a gas turns into a liquid
What is evaporation?
it is when a liquid turns into a gas
How will the surface area being larger cause a quicker rate of evaporation?
more particles will be closer to the surface to escape the liquid
Give an example of where the cooling of liquid can be very useful in the bodily functions.
sweating - when you exercise or get hot you sweat and as the water from the sweat on your skin evaporates it cools you down
How will the temperature of the gas being lower cause a quicker rate of evaporation?
the average particle energy in the gas is lower and so more particles will slow down enough and so will be able to clump together to form water droplets
How will the temperature being higher cause a quicker rate of evaporation?
the average particle energy will be higher and so they will have enough energy to escape
What happens to the particles (with the most kinetic energy) after they have evaporated from the liquid?
the average speed and kinetic energy of the particles decrease
How will the airflow being less cause a quicker rate of evaporation?
the concentration of the substance in the air will be higher and so the rate of condensation will be greater
How will the density being lower cause a quicker rate of evaporation?
the forces between the particles become weaker and so more particles will have enough energy to overcome these forces and so escape the liquid
How will the density being higher cause a quicker rate of evaporation?
the forces between the particles will be stronger and so fewer particles will have enough energy to overcome these forces of attraction and so will instead clump together to form a liquid
How will the airflow over the liquid being greater cause a quicker rate of evaporation?
the lower the concentration of an evaporating substance in the air it's evaporating into, the higher the rate of evaporation, a greater airflow above the liquid is replaced quicker so the concentration in the air will be lower
What happens to the temperature of the liquid after there has been a decrease in the average particles energy?
the temperature falls and so the liquid cools
When can particles evaporate from a liquid?
they can evaporate from a liquid at temperatures that are much lower than the liquids boiling point
