# Why are Earth's oceans salty?

As we all know water is $\ce{H2O}$, it does not contain sodium chloride. The ocean is a solution composed of water and a solute which is salt. I was wondering how the massive amounts of $\ce{H2O}$ in our oceans first mixed with salt? I'm sure the water didn't contain salt when it first got to the oceans so how did it get mixed with salt? Thanks.

• – Agriculturist Jul 8 '16 at 20:05
• But it is not in Chemistry Stack Exchange – Vishnu JK Jul 10 '16 at 17:21

Early history of Earth is a question to paleohydrology and paleochemistry. Briefly, water wasn't pure on the early stages of Earth.

Brief history of water on Earth. The planet was hot and seismoactive (lots of vulcanos) in the beginning. Water (as steam) escaped from magma, cooled down and precipitated on the Earth's surface. The surface already had salts on it, so it became saline from the very beginning. A better question is: how come we have fresh water in rivers and saline water in oceans? This separation is due to water cycle on our planet. Rivers bring dissolved salts to the ocean, then evaporates and precipitates over the land. Salts cannot evaporate (at any practical rate), so they stay in the ocean. This is similar to washing dishes. Consider this model: dish gets cleaner - that is a river; drain water gets dirtier - that is an ocean; drain water goes through purification and becomes clean before going to the supply pipe - this is evaporation of water from the surface of an ocean and precipitation over the land in our model.

The most common answar is- Water is a good solvent. When it flows, many kind of salts released by rocks dissolves in it. All these salty water goes to oceans and make them salty.

This reminds me of my school days when we had to watch this movie:

Hemo the magnificant

It's an old movie but worth the time to watch it.

Actually sea water contains traces of all known natural elements including sodium and chlorine ions and our blood is an analog of the sea water of which it evolved. Salt does not exist in water until the water is evaporated away.

• I'm completely baffled by your last sentence. It seems to contradict itself. – ringo Jul 21 '16 at 1:35
• It's not salt unless it is a solid so evaporation must take place to crystallize to salt. We call it salt water but it is the sodium and chlorine ions that make it "salty". – 3dalliance Jul 24 '16 at 19:04