The first law of thermodynamics may be expressed in the form
State, for a system, what is meant by:
: ..............................................................
: ..............................................................
State what is represented by a negative value of 
.
An ideal gas, sealed in a container, undergoes the cycle of changes shown in the figure below.
At point A, the gas has volume 
, pressure 
and temperature 
. The gas is compressed suddenly so that no thermal energy enters or leaves the gas during the compression. The amount of work done is 
so that, at point B, the gas has volume 
, pressure 
and temperature 
. The gas is now cooled at constant volume so that, between points B and C, 
of thermal energy is transferred. At point C, the gas has pressure and temperature 
. Finally, the gas is returned to point A.
Calculate the external work done on the gas during the expansion from point C to point A.
Complete the table below for the changes from:
point A to point B
point B to point C
point C to point A.
