Question

A substance has the following properties:

Sketch a heating curve for the substance, starting at $\mathbf{50}\mathbf{°}\mathbf{C}$

Short answer

The graph is plotted by taking the temperature in Celsius at the x-axis and Time at the y-axis.

AB=solid phase.Since,melting point is at -15⁰C

BC=phase change at constant temperatures, from solid-phase -15⁰ C to liquid phase -15⁰C.

The temperature changes due to the heat of fusion

CD = Heat goes into temperature change.

All Liquid gain to raise its temperature (from -15^0Cto 75⁹C)

DE =heat goes into phase change (from liquid to vapor)

The temperature does not change due to the heat of vaporization.

EF = Heat goes into temperature change (All gas), so the temperature rises.

Step-by-step solution

Heat of vaporization

The heat of vaporization is the amount of heat energy required to change the state of matter of a substance from liquid to gas or vapor.

The heat of vaporization mainly depends upon the intermolecular forcesbetween the molecules.

Heat of fusion

The heat of fusion is the amount of heat energy required to change the state of matter of a substance from solid to liquid.

Explanation 

The graph is plotted by taking the temperature in Celsius at the x-axis and Time at the y-axis.

AB=solid phase. since the melting point is at -15⁰C

BC=phase change at constant temperatures, from solid-phase -15⁰ C to liquid phase -15⁰C.

The temperature changes due to the heat of fusion

CD = Heat goes into temperature change.

All liquids gain to raise the temperature (from -15^0Cto 75⁹C)

DE =heat goes into phase change (from liquid to vapor)

Temperature does not change due to the heat of vaporization.

EF = Heat goes into temperature change (All gas), so the temperature rises.