Question

heating and cooling curves
heating curves
a heating curve shows how the temperature (y - axis) changes as a substance is heated up at a constant rate over time (x - axis)
point a: substance exists at a solid state. as time passes, heat is added to the substance. this causes the molecules of the substance to move more rapidly which we detect by an increase in temperature of the substance.
point b: the temperature of the substance is 80°c which is the melting point (t) of water. the solid begins to melt. both solid and liquid are present.

• the energy put in the substance between minutes 5 - 9 (between b & c) was used to convert the substance from a solid to a liquid. this heat energy is called the \latent heat of fusion.\

point c: the substance is completely ____ and in the ____ state.

• between 9 & 13 minutes (between c & d) the added energy increases the ______ of the substance

Explanation:

• Heating curves show temperature change over time.
• At point A, substance is solid. Heat makes molecules move (kinetic energy), increasing temperature.
• Point B: Temperature is \(0^{\circ}C\) (melting point of water). Solid melts. Solid and liquid co - exist.
• Between B - C (latent heat of fusion), energy converts solid to liquid.
• Point C: Substance is completely melted (liquid state).
• Between C - D: Added energy increases temperature (kinetic energy of liquid molecules).

Answer:

• Point A: Temperature, Time, Solid, Heat, Move (kinetic), Temperature
• Point B: \(0^{\circ}C\), Melting, Melt, Solid, Liquid, Solid, Liquid
• Point C: Melted, Liquid, Temperature