Water is a powerful solvent

Marine Science - Ocean Chemistry

What is the hydrologic cycle, and what powers it?

The hydrological cycle is the continuous circulation of water between the ocean, atmosphere, and land. It is powered primarily by solar radiation, with some assistance from geothermal energy.

Where is most of Earth’s surface water found, and how much is freshwater?

About 97.5% of Earth’s surface water is in the ocean. About 1.8% is locked in glaciers and ice caps, while only about 0.64% is freshwater in rivers, lakes, wetlands and groundwater.

What happens to water as it moves through the hydrologic cycle?

About 85% of atmospheric water comes from oceans evaporation. Water vapour condenses into clouds and produces rain and snow. About 80% of precipitation falls back into the ocean, while the remaining 20% falls on land and eventually returns to the ocean.

What are the approximate residence times of water in the ocean and atmosphere?

Water remains in the ocean for about 4100 years on average, but water vapour remains in the atmosphere for only about 9 days.

Why is water such an effective solvent?

Water is a polar molecule, meaning it has slightly positive end and a slightly negative end. These opposite charges allow water to attract and separate charged particles in compounds, making water capable of dissolving more substance than almost any other liquid.

What is the difference between a solution and a mixture?

A solution is a uniform composition, with solute homogeneously dispersed in a solvent.

A mixture contains substances that retain their separate identities, so its properties can vay from place to place.

What are diffusion and saturation?

Diffusion is random movement of substances through a solution.

Saturation occurs when no more of a substance can dissolve because the rate of dissolving equals the rate of precipitation (re-forming crystals).