Does salt make boiling water decrease?

Answer 1

No, it increases the boiling point. becomes lower. Let's look at why a salt water solution has a freezing point below zero, and how you can use this fact to make ice cream!

At the right is a container of water with an ice cube in it. The water and ice are at 0°C, which is the melting point of ice and the freezing point of water.

Molecules of ice are constantly escaping into the water (melting), and molecules of water are being captured on the surface of the ice (freezing).

When the rate of freezing is the same as the rate of melting, the amount of ice and the amount of water won't change. The ice and water are said to be in dynamic equilibrium with each other. The ice is melting, and the water is freezing, but both are occurring at the same rate, so there is no net change in either quantity.

This balance will be maintained as long as the water stays at 0°C, or unless something happens to favour one of the processes over the other.

Here is the same container, but where the water temperature is -10°C.

The molecules of water are moving more slowly, because they contain less heat. These slower-moving water molecules are more easily captured by the ice, and freezing occurs at a greater rate than melting.

Because there more water molecules being captured by the ice (being frozen) than there are ice molecules turni water, the net result is that the amount of water decreases, and more freezing is happening than melting, the water eventually all turns to ice.

This time we've warmed the water to 10°C.

Now the water of the ice, so not very many of them freeze. Freezing occurs at a slower rate than melting.