Physical Properties of Water

Abstract

The water molecule is electrostatically charged with a negative site on one side and two positive sites on the other. Attractions between oppositely-charged sites on adjacent water molecules are stronger than typical van der Waals attractions among molecules and are called hydrogen bonds. The molecules in solid (ice) and in liquid water exhibit stronger mutual attractions than do the molecules of other substances of similar molecular weight. This results in water having maximum density at 3.98 °C, high specific heat, elevated freezing and boiling points, high latent heats for phase changes, remarkable cohesive and adhesive tendencies resulting in strong surface tension and capillary action, and a high dielectric constant. Light also penetrates readily into water and is strongly absorbed. The pressure of water at a given depth is a combination of atmospheric pressure and the weight of the water column above that depth (hydrostatic pressure). Water refracts light making underwater objects appear to be at lesser depth. The physical properties of water are of intrinsic interest, but they also are critical factors in geology, hydrology, ecology, physiology and nutrition, water use, engineering, and water quality measurement.