The suffixes P and V refer to constant pressure and constant volume conditions respectively. The heat capacity ratio is important for its applications in thermodynamical reversible processesespecially involving ideal gases ; the speed of sound depends on that factor. To understand this relation, consider the following thought experiment. A closed pneumatic cylinder contains air.
In order to extend the discussion to solids and liquids we need to get more quantitative in two ways.
One is to discuss how much the temperature of a body changes when its internal energy in increased by a certain amount. The other is to ask what happens when a substance changes phase from a solid to a liquid or liquid to a gas. Start by introducing the equation for specific heat capacity c SHC and defining the terms.
Work through a simple calculation. Understanding this equation will help solidify ideas about temperature and energy and how they differ. A possible analogy was supplied by Richard Feynman. He suggested thinking of heat energy as being like water, and temperature as wetness.
A towel can have different amounts of fluffiness, so take more or less water to make it wet. The anomalously large SHC of water should also be discussed as it is particularly important for the development and maintenance of life on Earth.
Perhaps the most common is specific heat capacity. Solids, liquids and gases are three of the different phases of matter superfluids and plasmas are two others.
NB Here, by a plasma, we mean an ionised gas, not a biological fluid. Thus melting, boiling etc are changes of phase.
Each phase can exist in a variety of states depending upon e. There are a number of points to note here: If specific heat capacity is constant, the temperature will rise at a uniform rate so long as the power input is constant and no energy is lost to the outside.
There are large potential heat losses if the substance is not well insulated.
These can be accounted for but in most cases students will not do so quantitatively. They should calculate their value and make a comparison with data book values.
They should be able to think of a number of reasons why their value does not match that in the data book. Several different methods of determining the SHC of liquids and solids are given in the links below. Choose those best suited to your pupils and available equipment. Measuring the specific heat capacity of a metal TAP The specific heat capacity of water and aluminium It is useful to compare electrical methods of measuring the specific heat capacity of a solid and liquid including the continuous flow calorimeter for a liquid.
Measurement of specific heat capacities Worked example: Calculation involving C This example deals with the mixing of liquids at different temperatures. Find the temperature of the mixed water, assuming no significant heat loss during the mixing.
If there is no heat loss and no work done then the total energy of the system at the end is the same as at the start.Whereas in recuperators, where heat is transferred directly and immediately through a partition wall of some kind, from a hot to a cold fluid, both of which flow simultaneously through the exchanger, the operation of the regenerative heat exchanger involves the temporary storage of the heat transferred in a packing which possesses the necessary thermal capacity.
Habitat Location where a plant or animal lives. Hadean Geologic eon that occurred from to million years ago. The Earth's oldest rocks date to the end of this time period. Hadley Cell Three-dimensional atmospheric circulation cell located at roughly 0 to 30° North and South of the equator.
Worked Examples of Relative Molecular Mass Calculations Calculating the Relative Molecular Mass of a Diatomic Molecule. Carbon monoxide is a diatomic molecule, a molecule made up of two atoms: an atom of carbon (C) and an atom of oxygen (O).
"Air" is the name we give to the mixture of gases which make up the Earth's atmosphere.
The composition, physical, and chemical properties of air are very similar everywhere. Heat Capacity - C - is a characteristic of an object - the amount of heat required to change its temperature by one degree.. Heat Capacity has the units of energy per degree. The amount of heat supplied to heat an object can be expressed as: Q = C dt (1).
The heat capacity at constant volume, C v, is the derivative of the internal energy with respect to the temperature, so for our monoatomic gas, C v = 3/2 R. The heat capacity at constant pressure can be estimated because the difference between the molar C p and C v is R; C p – C v = R.