Why Do Impurities Lower The Melting Point?
When you say melting, we talk about ‘solid, things. Impurities affect the general composition of the ‘matter, whatever form it may be. A good example would be the boiling point of water, as it is water alone has its own boiling point. If other substances are added to the water (for example salt) it will increase the time for it to reach its boiling point, since new ‘matter, is added to the solution.
The same can be said about solid things, the melting point may increase or decrease depending on the solution that is added to the ‘compound,. A compound is a solution or combination of two or more elements. Since every element have their specific melting, freezing and boiling points, an impurity would affect these conditions and may rather decrease or increase the time or temperatures needed to meet the necessary conditions.
Different types of matter undergo different changes depending on the temperature. Some liquids turn to gas when subjected to high temperatures. Others liquids become solid when exposed to freezing temperatures. When a solid turns into a liquid state, the process is called ‘melting, and it requires high temperatures to do so. This is the process on which the substance of the solid matter slowly changes into a liquid matter.
The process on which the matter has an equal amount of solid and liquid composition is the stage where the freezing/melting point begins. It is safe to say that impurities present in the ‘matter, whether solid, liquid or gas affects the general composition of the element. The more the impurities the longer the boiling point and the lower the melting point of these elements.
Try making experiments of your own to yield better results. Just note that the results may differ depending on the amount of impurities you will add to the ‘matter, at hand.