Oceanography For Thought

A magician places an egg in a glass of water. It doesn't float. Next, he gets another glass and places the egg in the water. This time the egg floats. How did the magician do this trick?!

It's simple: he used salt water. Let me explain. The magician put the egg into fresh water first. The egg didn't sink because it is denser than the fresh water. However, salt water is denser than fresh water or the egg, so the egg floated.

A way for the magician to impress the scientific community is for him to make an egg disappear when it gets into the water. I am uncertain if it's possible, but that would actually be impressive.

Over 70% of the world is covered in saltwater, wouldn't it be cool (pun intended) for us to be able to turn that water into usable freshwater?

Actually, that is being done. Huge desalination plants like Ras Al Khair (in Saudi Arabia) are pumping out millions of cubic meters of fresh, potable water per DAY. In fact, the aforementioned Ras Al Khair plant uses two methods of desalination: reverse osmosis and multi-stage flash distillation.

Osmosis is when a less concentrated substance (fresh water in this case) passes through a membrane and flows into a more concentrated substance (salt water). We can reverse this flow by pressurizing the salt water, forcing it to go through the membrane (which doesn't let salt molecules through), and flow into the fresh water.

Flash distillation is when water is subjected to a very intense heat, evaporating it. Next, the steam goes to a container where it is cooled and becomes liquid water again.

Using these two processes, the Ras Al Khair plant distills around 1.03 million cubic meters of fresh water a day.