Question

Which statement describes the phase change that occurs when dry ice is placed in an open container at room temperature?
a)Dry ice undergoes sublimation, an exothermic change, at room temperature.

b)Dry ice undergoes sublimation, an endothermic change, at room temperature.

c)Dry ice undergoes deposition, an endothermic change, at room temperature.

Answer 1

Not sure but it should be option a

Answer 2

b) Dry ice undergoes sublimation, an endothermic change, at room temperature.

Explanation:

Dry ice is actually carbon dioxide frozen to -109.3 degree F (-78.5 degrees C). Dry ice kept in open takes heat from the surrounding and goes under a phase change process where it directly changes to gaseous states of carbon dioxide from solid state, skipping the liquid state.

The process in which the solid changes its phase to gaseous directly from solid state is called sublimation.

For the dry ice to sublimate it requires heat which it takes from the surroundings that is why the reaction is endothermic.