Question

12. Define terms system and surroundings. What does it mean to say a system and its surroundings are in thermal equilibrium?

What determines the directionality of energy transfer as heat?

Answer 1

Ref: chemwiki.ucdavis.edu/Core/Physical_Chemistry/Thermodynamics/A_System_And_Its_Surroundings

System: It is a part of the universe. It is two types (i) open system, (ii) closed system.

Surroundings: rest of the universe surrouning the system.

For example: Ice cube is system, hot iron rod.

From these two examples how the surroundings behaves thermally equillibrium with system.

Surroundings means consiederable area whic is in equillibrium with system.

Ice cube in a small beaker is consierable example for system (ice cube) an surroundings (small beaker).

In open system : energy & matter will be transferred but in close systems, only energy will be transferred.

for the directionality of energy transfer as heat, go through ref: http://www.ask.com/home-garden/determines-direction-heat-flow-f326c09abef931a0

The amount of heat enegry of a system is enthalpy, it is irectly propotional to the temperature of the system.