Heat and States of Matter Chapter 9: Heat and States of Matter Section 1: Temperature and Thermal Energy

Kinetic Theory of Matter Temperature and Thermal Energy 1 Kinetic Theory of Matter The motion of the particles in matter is described by KINETIC THEORY of matter. Matter is composed of particles that are atoms, molecules, or ions that always are in random motion.

Temperature and Thermal Energy 1 Temperature The TEMPERATURE of a substance is a measure of the average kinetic energy of its particles. The SI unit for temperature is the KELVIN (K).

Temperature °C = (5/9)(°F – 32) °F = 1.8 (°C) + 32 1 Temperature and Thermal Energy 1 Temperature Commonly used temperature scales are the Celsius scale and the Fahrenheit scale. Conversion Equations: °C = (5/9)(°F – 32) °F = 1.8 (°C) + 32

Temperature °F = 1.8 (°C) + 32° °F = 1.8 (22°) + 32° °F = 39.6° + 32° Temperature and Thermal Energy 1 Temperature Using Conversion Equations: Room temperature is considered to be 22 °C What is this temperature in °F? °F = 1.8 (°C) + 32° °F = 1.8 (22°) + 32° °F = 39.6° + 32° °F = 71.6 °F

Temperature °C = (5/9) (°F – 32) °C = (5/9)(212° – 32) Temperature and Thermal Energy 1 Temperature Using Conversion Equations: Water boils at 212 °F at standard temperature and pressure What is this temperature in °C? °C = (5/9) (°F – 32) °C = (5/9)(212° – 32) °C = (5/9) (180°) °C = 100°F

Temperature and Thermal Energy 1 Thermal Energy The sum of the kinetic and potential energies of all the particles in an object is the THERMAL ENERGY of the object. The increase in an object’s speed doesn’t affect the random motion of its particles, so it doesn’t affect its thermal energy.

Temperature and Thermal Energy 1 Heat HEAT is thermal energy that flows from something at a higher temperature to something at a lower temperature. Heat is a form of energy, so it is measured in joules.

Temperature and Thermal Energy 1 Specific Heat The amount of thermal energy needed to raise the temperature of 1 kg of some material by 1°C is called the SPECIFIC HEAT of the material. Specific heat is measured in joules per kilogram per degree Celsius.

Change in Thermal Energy (J) = Temperature and Thermal Energy 1 Changes in Thermal Energy Change in Thermal Energy (J) = mass (Kg) x change in temperature (C) x specific heat ( J/Kg°C) Q = m (Tf – Ti) C J = (Kg) (°C ) J Kg °C

Measuring Specific Heat Temperature and Thermal Energy 1 Measuring Specific Heat The specific heat of a material can be measured using a device called a CALORIMETER. In a calorimeter, a heated sample transfers thermal energy to a known mass of water.

Measuring Specific Heat Temperature and Thermal Energy 1 Measuring Specific Heat The thermal energy released by the sample is equal to the thermal energy absorbed by the water.

Question 1 1 How is temperature related to kinetic energy? Section Check 1 Question 1 How is temperature related to kinetic energy?

Section Check 1 Answer Temperature is a measure of the average kinetic energy of the particles in an object or material. As the temperature increases, the average speed of the particles increases.

Section Check 1 Question 2 How does thermal energy differ from kinetic energy? Answer Thermal energy is the sum of the kinetic and potential energy of all the particles in an object.

Section Check 1 Question 3 The amount of heat that is needed to raise the temperature of 1 kg of a material by 1º C is called the __________ of the material. density mass C. specific heat D. thermal energy

Section Check 1 Answer The answer is C. Specific heat is measured in joules/kilogram °C.