Heat and Heat Technology

Name ______Date ______

Physical Science 9

Chapter 10

Heat and Heat Technology

Test Study Guide

SECTION 1: TEMPERATURE

Temperature – a measure of how hot or cold something is; specifically, a measure of the average kinetic energy of the particles in an object

• Remember that the temperature depends upon the AVERAGE kinetic energy, not how much you have of the substance.

Thermal expansion – an increase in the side of a substance in response to an increase in the temperature of the substance

• Thermometers are filled with mercury or alcohol – they stay liquids over a large temperature range.
• Thermometers use thermal expansion to measure temperature

Item / Use / Picture
Expansion Joints / keep bridges from breaking when the temperature changes /
Bimetalic Strips / The coiling and uncoiling of the two different metals turns heaters and air conditioners on and off. /

Fahrenheit / Celsius / Kelvin
Used by / The United States / The rest of the world / Scientists
Measured in… / degrees / degrees / kelvins
Absolute 0 (all molecular motion stops) / -495 ° / -273 / 0

Temperature Conversions

To convert / Use the equation
oC to oF / oF = (9/5 x oc) + 32
oF to oC / oC = 5/9 x (oF – 32)
oC to K / K = oC + 273
K to oC / oC = K – 273

SECTION 2 WHAT IS HEAT?

Heat – energy transferred between objects that are different temperatures

Thermal Energy – Kinetic Energy of a substances atoms. Measured in joules (j)

• depends partly on temperature
• depends on how much of a substance there is
• Energy will pass from the warmer object to the cooler object until both have the same temperature

Thermal Conductor / A material through which energy (heat) can be transferred easily.
Examples: Curling iron, copper pipe, iron skillet
Thermal Insulator / A material that reduces or prevents the transfer of heat
Examples: Oven Mitt, Plastic, Insulation
Ways Thermal Energy is Transferred / Definition / Example
Conduction / transfer of thermal (heat) energy from one substance to another through direct contact / Spoon in hot soup (the end of the spoon will warm up because the transfer of energy occurs all the way up the handle)
Convection / Transfer of thermal energy by the circulation or movement of a liquid or gas / Repeated rising and sinking of water during boiling
Radiation / Transfer of energy as electromagnetic waves / Coils of a portable heater by radiating visible light and infared waves

Specific Heat – the amount of energy needed to change the temperature of 1kg of a substance by 1°C

Energy transferred by heat cannot be measured directly – it must be calculated using specific heat, mass, and change in temperature

Heat (J) = specific heat (J / g °C) x mass (g) x change in temperature (°C)

SECTION 3 MATTER & HEAT

States of matter – physical forms of matter (sold, liquid, and gas)

Change of state – change from one physical state to another (ex. Solid to liquid)

Thermal energy transferred during a change of state does not change a substance’s temperature – it causes a substance’s particles to be arranged.

A calorimeter can measure energy changes by measuring heat.