Heating and Cooling Flashcards
What is the change of state called when a gas turns into a liquid?
Condensing
What is the change of state called when a liquid turns into a solid?
Freezing
What is the change of state called when a liquid turns into a gas?
Boiling
What is the change of state called when a solid turns into a liquid?
Melting
What is temperature?
Temperature is a measure of how hot or cold a substance is, measured in degrees Celsius, °C.
What is heat?
Heat is a measure of the amount of energy contained in an object’s thermal energy store, measured in joules, J.
What is thermal energy?
Energy stored in heated objects
What is the direction of movement of energy between two objects of different temperatures?
Hot to cold
Which statement is true?
- Energy transfers from the hotter to the cooler object.
- Energy transfers from the cooler to the hotter object.
- Energy transfers from the hotter to the cooler object.
How long will the transfer of energy between two objects or areas at different temperatures continue for?
Until both objects are at the same temperature.
What is the law of conservation of energy?
Energy cannot be created or destroyed, only transferred or stored.
What causes an object to have energy in its thermal energy store?
The vibration or movement of its particles.
What happens when particles gain more energy?
The particles vibrates more.
In the example shown, what factor affects the amount of energy contained in the object’s thermal energy store?
Its temperature.
In the example shown, what factor affects the amount of energy contained in the object’s thermal energy store?
Its mass.
Solids transfer energy by ___________
Conduction
Fluids (liquids and gases) transfer heat by ___________
Convection
Which method of heat transfer causes heat to be transferred to the air above a cup of hot tea?
Convection
A solid is a material with particles . . .
that vibrate around fixed positions.
What is a thermal conductor?
A substance that transfers energy by conduction quickly.
What is a thermal insulator?
A substance that transfers energy by conduction slowly or not at all.
A material that is a poor thermal conductor is called a __________________
thermal insulator.
In what situation does conduction occur?
- in the absence of particles
- in substances with touching particles
- in fluids
- in substances with touching particles
What happens to the particles in a substance as it’s being heated?
- They gain energy and vibrate more.
- They gain energy and start to vibrate.
- They gain energy and vibrate more.
What effect does heating a particle in one part of a substance have on the nearby particles?
The heated particles collide with nearby particles, causing them to vibrate more as well.
Describe the stages of energy transfer by conduction:
- Particles that are heated gain energy.
- The increase in energy causes the particles to vibrate more.
- The particles that are vibrating more collide into the particles around them, transferring the energy.
- The movement of energy through a solid is called conduction.
Describe how conduction occurs through a metal rod that is being heated by a Bunsen burner:
- The Bunsen burner flame heats the metal rod.
- As they are heated, the particles in the rod gain energy and vibrate more.
- The heated particles collide with nearby particles, causing them to also vibrate more.
- As more and more particles vibrate, there are more and more collisions, so energy transfer continues throughout the metal rod.
- Eventually the temperature of the whole rod increases.
Why is conduction very slow in liquids?
The particles are loosely packed, so they don’t collide often.
Why doesn’t conduction occur in a vacuum?
There are no particles in a vacuum.
How is energy transferred through a solid?
By conduction
Why does conduction rarely happen in gases?
The particles are spread out, so the particles rarely collide.
