Heat changes matter

Heat changes matter

The Effects of Heat Flow on Matter

• When objects are heated, their volume generally increases. This increase in size called expansion.  

• When objects are cooled, their volume generally decreases.  This decrease in size is called contraction.

• Heat flows from a place of high temperature to a place of lower temperature.

Heating and cooling solid

• When a solid (metal) is heated, its particles (atoms) receive more heat energy and vibrate faster.

• The particles occupy more space and move further apart from one another, keeping the same relative positions. So the solid expands

• On cooling the vibrations slow down and the particles return to their original positions. So the metal contracts.

Heating and cooling liquid

• When the water is heated, its particles (molecules) receive more energy and move further apart from one another in all directions.

• The water takes up more space and its volume expands.

• The water level in the glass tube falls a little at first because the flask expands before the water.

Heating and cooling gas

• a) When the air is warmed, the gas particles (molecules) receive more kinetic energy and move outwards very quickly in all directions. So the air expands very fast.

• b) Gases can expand very fast because there is : 

   i. Plenty of space between the particles.

  ii. Hardly any force of attraction between the particles.

• c) All gases expand at about the same rate when heated.

Multiple Choice

A tool used to measure temperature.

• scale
• graduated cylinder
• themometer
• magnifying glass

Multiple Choice

Which of the following shows heat loss?

• boiling water

• eggs cooking on a pan

• ice cream melting under the sun

• hot bowl of soup becoming room temperature

Multiple Choice

Which of the following shows heat gain?

• water turning into ice

• shivering in a cold room

• ice cream melting under the sun

• hot bowl of soup became room temperature

Multiple Choice

What happens when something loses heat?

• it becomes hotter

• it becomes colder

Multiple Choice

What happens during heat loss?

• the object will expand

• the object will contract

Multiple Choice

What happens during heat gain?

• the object will expand

• the object will contract

Multiple Choice

What happens when something gains heat?

• it becomes hotter

• it becomes colder

Multiple Choice

Which is NOT a heat source?

• the Sun

• iron

• oven

• pot

Multiple Choice

While camping the boy rubbed two sticks together for a minute.  What was the boy creating?

• cold
• electricity
• heat
• light

Multiple Choice

A type of energy that moves from a hot object to a cold object.

• conductor
• heat energy
• insulator
• themometer