G6 – Why is the Ocean Salty? 600-700L – 03

Imagine this scenario. You have a beaker of water. Think of the beaker as the Earth’s ocean basins. You fill the beaker with water. Then you add a single grain of salt. This represents fresh water. If you were to taste this water, it would not taste salty. You allow the water in the beaker to evaporate. The single grain of salt will be left behind. You repeat this entire process over and over again. Each time, you add another grain of salt. Now if you tasted the water, you would notice the salt. This result represents salt water. This process happens every day due to the water cycle. Salt enters our ocean and water is evaporated.

Most evaporation occurs over the ocean. Most of this evaporated water falls as rain back into the ocean, but not all. Air currents move around Earth. As they do, they also push water vapor and clouds. What started as salt water is returned to land as fresh water in the form of precipitation. How can this happen?

Salt dissolving in water is a physical change. Many physical changes are reversible. This means the salt and the water can be separated from one another. This occurs when water is allowed to evaporate. As it does, the salt is left behind. In fact, this process explains how much of the salt we use today is produced.

In warm and sunny climates, areas of land are flooded with salt water. The water is allowed to stand in shallow pools until it evaporates. Once the water has evaporated. What is left behind is a layer of salt that can be recovered and sold.