Question

Which of the following phase changes is exothermic?

gas to solid
solid to liquid
solid to gas
liquid to gas

Answer 1

The exothermic phase change is solid to liquid.

Step-by-step explanation:

The phase change that is exothermic is solid to liquid. When a solid changes to a liquid, heat is released to the surroundings. This is because energy is being released as the particles in the solid slow down and come closer together to form a liquid. An example of this is when ice (solid) melts to form water (liquid) and heat is released.

Answer 2

Answer:

gas to solid

Step-by-step explanation:

Exothermic means the release of heat. Any transformation from a less ordered to a more ordered state releases energy. This is represented by the change of a liquid to solid, gas to liquid, or gas to solid. Vise versa endothermic is the transformation from a more ordered state to a less ordered state represented by solid to liquid, liquid to gas, and solid to gas.