Question

State the effect of presence of impurity on the melting point of ice. Give one use of it.

Answer 1

Hint: We should be mindful in this issue of the impact of impurities on the melting point. A substance's melting point decreases with an increase in the concentration of impurities .

Complete Step-by-Step solution:
The melting point is known as the temperature a material melts at. Or we can tell the temperature it changes from solid to liquid at. Solid and liquid phases occur in equilibrium at the melting point.
We know that the presence of impurities in a substance results in a lower melting point due to a process called melting point depression.
Hence, if we add some impurities in ice, then the melting point of ice decreases from 0 °C to -22 °C on mixing salt in it in proper proportion.
Depression at melting point occurs because of the existence of the solid state of a substance. Many of the solids, such as ice, form as crystalline ions or molecular repeating lattices. This lattice is kept together by forces between molecules which create a strong, stable structure. The solid has to be heated to a certain temperature for destruction of this structure and melting of the solid. The presence of impurities therefore weakens the lattice, rendering it less stable. The compound then melts at a lower temperature.
Use of adding impurities in ice: salt is added to the frozen streets helps to melt the ice. This decreases the melting point of the ice and the ice melts easily.

Note: In this type of question, we should have some basic knowledge about melting point and impurities. Then we have to find out the mechanism that will happen if we add some impurities in a substance. Through this we will understand the effect of impurities and the use that why we add it and we will get the answer.