When is the melting point of ice

In their freezers. How cold is the freezer? Have they ever observed ice freezing outside? What was the temperature? The children may not know the numerical answer, but they will discover it in the activity.

Explain to the children that this is called the "Freezing Point" of water. Ask the children to make predictions about the melting point of ice.

At what temperature do they think ice melts? Again, the children may or may not know. Invite the children to think about their experiences. Would ice melt on a hot summer day outside in the Sun?

What might that warm outside temperature be? Pure crystalline solids melt over a very narrow range of temperatures, whereas mixtures melt over a broad range of temperatures. The temperature of the reverse change from liquid to solid is called the freezing point or crystallization point.

For most substances the melting point and freezing points are equal. During the melting process, till all the ice melts, the temperature of the system does not increase until after the melting point is reached. The whole of the supplied heat energy is consumed in increasing the potential energy of the ice molecules.

The kinetic energy of the molecule does not increase further, and the temperature does not increase, so long as the melting continues. The quantity of heat required to completely change 1 kg of ice into water at atmospheric pressure at its melting point is called latent heat of fusion. For ice, it is 3.

What's the Point? Water can exist in different states; ice is the solid state of water. Adding salt — or other substances — to ice lowers the melting point of ice.

Have them annotate their predictions in their Ice Investigator Journal. Divide the children into teams of four to six and invite them to perform an experiment that will test their predictions!

Distribute the materials, including the plate, salt, two ice cubes, and magnifying glass to each team. Let the melting begin! Invite the children to sprinkle salt on top of one of their ice cubes, being careful not to get any salt on the second cube. However, while liquids are fluid, solids are not. The particles of most solids are packed tightly together in an orderly arrangement. The motion of individual atoms, ions, or molecules in a solid is restricted to vibrational motion about a fixed point.

Solids are almost completely incompressible and are the densest of the three states of matter. As a solid is heated, its particles vibrate more rapidly as the solid absorbs kinetic energy.

Eventually, the organization of the particles within the solid structure begins to break down and the solid starts to melt. The melting point is the temperature at which a solid changes into a liquid.

At its melting point, the disruptive vibrations of the particles of the solid overcome the attractive forces operating within the solid. As with boiling points, the melting point of a solid is dependent on the strength of those attractive forces.