First Law of Thermodynamics

First Law of Thermodynamics

The first law of thermodynamics is shared with most of science; it is

one of the fundamental principals that have shaped our understanding

of the working world.

TOTAL ENERGY OF THE SYSTEM AND IT'S SURROUNDINGS IS CONSTANT or ENERGY

IS CONSERVED, Brings back that long established idea that nothing can

be created or destroyed. How do we know this? This is an empirical

law, which means that we know that energy is conserved because of many

repeated experiments by scientists. It's been observed that you can't

get any more energy out of a system than you put into it.

Latent heat

Latent Heat is defined as the heat which flows to or from a material

without a change to temperature. The heat will only change the

structure or phase of the material. E.g. melting or boiling of pure

materials.

One very good illustration of latent heat in action is observed when

we reduce ice to water. If we imagine a bucket of ice on the floor in

an average temperature room (about 30 degrees Celsius) .The ice

doesn't instantly liquidize, nor does the room instantly freeze.

Instead the temperature of the ice rises until it reaches zero degrees

Celsius whereupon it begins to melt. During the entire melting process

the contents of the bucket remain at zero degrees, however the room

temperature would drop indicating that it was putting heat energy into

the melting process. This heat energy is described as latent heat.

Specific heat

The specific heat capacity of a solid or liquid is defined as the heat

required to raise unit mass of substance by one degree of temperature.

Some substances have more resistance to temperature change than others

so more energy is required to alter the temperature. This can be very

useful particularly in cooling systems.

Imagine trying to fry an egg in a frying pan with a steel handle, the

handle would conduct the heat very nicely to your hand. However the

high carbon plastic sheath on most modern pans is very resistant to