Ocean Water Chemistry

You now know many of the amazing properties of water. A water molecule is made of one oxygen (O) atom and two hydrogen (H) atoms joined together by a chemical bond. As a polar molecule, individual water molecules tend to cling to one another and to other polar molecules. This characteristic is the reason water is known as the universal solvent. You also learned that water exists in three different states: solid, liquid and gas.

Seawater is salty because there are substances, such as salts, dissolved in it. Salinity varies from place to place due to changes in the amount of pure water present. Many characteristics of seawater change with depth, including salinity, density and temperature. The three main gases dissolved in seawater are carbon dioxide, oxygen and nitrogen.

More than two-thirds (2/3) of the Earth's surface is covered with water. For this reason, the water cycle is very important, as it not only provides water, but also carries with it many nutrients necessary for life. Naturally, seawater has a pH of about 8.1, making it slightly basic. However, as we continue burning large amounts of fossil fuels, the resulting increase in atmospheric carbon dioxide has caused seawater to acidify slightly. This slight change can make survival difficult for some species.