Chapter Objectives and Summaries
for the Oxford University Press text by Walding, Rapkins and Rossiter:-
" NEW CENTURY Senior Physics - Concepts in Context "
CHAPTER 10 Heat and Temperature.
Knowledge of subject matter
- Identify the different temperature scales.
- Solve simple problems related to conversion from one scale to another.
- Identify different types of thermometers.
- Define heat and temperature and distinguish between them.
- Define heat capacity.
- Define specific heat capacity.
- Solve simple problems involving heat capacity and specific heat capacity.
- Discuss the importance of the high specific heat capacity of water.
- Explain what is meant by the terms: melting, boiling, freezing, condensation, evaporation, vaporization, and solidification.
- Distinguish between boiling and evaporation.
- Solve simple problems involving latent heats of fusion and vaporisation.
- Solve problems relating to data obtained from the use of thermometers and calorimetry.
- Read and be able to understand temperature verses heat graphs.
- Apply the particle model to explain thermal effects.
COMPLEX REASONING PROCESSES
- Solve complex problems relating to specific heat, latent heat, and heat exchange.
- Propose reasons for observable thermal energy effects in nature.
CHAPTER 10 SUMMARY
- Temperature is often regarded as a measure of the degree of hotness or coldness of an object. Temperature is measured using a thermometer. Temperature is a measure of the average kinetic energy of the particles of a substance.
- The most commonly used temperature scale is the celsius scale.
- The temperature scale most commonly used in scientific work is the kelvin scale.
- To convert Celsius temperature to Kelvin temperature use the equation: K = oC + 273.
- The coldest possible temperature - absolute zero - occurs at -273.15 oC, or 0 K. This is the temperature at which particle motion stops.
- Thermometers use some physical property of a substance that changes as temperature changes. The most common is the liquid in glass thermometer.
- Heat is a form of energy.
- Heating is process of energy transfer due to a temperature difference.
- The internal energy or thermal energy of a substance is the sum of the kinetic and potential energies of the particles.
- Internal energy of a substance can be increased by doing work on, or by heating the substance.
- The specific heat capacity (c) of a substance is the quantity of heat required to raise the temperature of 1 kg of the substance by 1 oC. It is measured in J kg-1 K-1.
- The quantity of energy (Q) transferred to or from a substance is given by the equation:
Q = m.c.DT.
,Where Q is the energy in joules, m is the mass of the substance in kg, c is the specific heat capacity in J kg-1 K-1, and DT is the change in temperature kelvin (or celsius degree).
- In a closed system the thermal energy lost by one object is equal to the thermal energy gained by the other. Conservation of energy.
- A change of state from a solid to a liquid is called melting or fusion. The reverse is called freezing or solidification. A change of state from a liquid to a gas is called vaporisation. The reverse is condensation.
- To bring about a change of state requires energy (latent heat).
- The energy required to change 1 kg of a substance from a solid to a liquid without change in temperature is called the specific latent heat of fusion (Lf).
- Q = m Lf....Where Lf is the specific latent heat of fusion measured in J kg-1.
- The energy required to change 1 kg of a substance from a liquid to a gas without change in temperature is called the specific latent heat of vaporisation (Lv).
- Q = m Lv, Where Lv is the specific latent heat of vaporisation.
- Evaporation is the escape of the fastest molecules from the surface of a liquid and can occur at any temperature. It results in a cooling effect.
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