Saline water

Saline water, also called salt water, is water with lots of dissolved salts, mostly sodium chloride. It is saltier than brackish water but not as salty as brine. Scientists measure salt in water using parts per thousand or parts per million.

There are different levels of saline water. Slightly saline water has a small amount of salt. Moderately saline water has more, and highly saline water has even more. Seawater is highly saline, with a lot of salt in it.

The amount of salt that can mix with water changes a little with temperature. This helps us know how much salt water can hold in different weather.

Properties

Saline water, also called salt water, has lots of dissolved salts, mostly sodium chloride. It is saltier than brackish water but not as salty as brine. We measure the amount of salt in parts per thousand (permille, ‰) and parts per million (ppm).

At 100 °C, saturated sodium chloride brine is about 28% salt by weight. At 0 °C, brine can only hold about 26% salt. At 20 °C, one liter of water can dissolve about 357 grams of salt.

The thermal conductivity of seawater (3.5% dissolved salt by weight) is 0.6 W/mK at 25 °C. The thermal conductivity changes with salinity and temperature. We can measure salt content with a salinometer.

The density of brine at different concentrations and temperatures can be found using a special equation.

Electrolysis

A small amount of hydrogen gas is made by electrolysis. This hydrogen is usually made when we produce chlorine.

• 2 NaCl(aq) + 2 H₂O(l) → 2 NaOH(aq) + H₂(g) + Cl₂(g)