2.2 PROPERTIES OF WATER
Like all of the other molecules, a water molecule (H20) is neutral. A water molecule is polar because the electrons between the oxygen and hydrogen are unevenly distributed. A water molecule can form hydrogen bonds. Hydrogen bonds are weaker than the ionic or covalent bonds but it is able to form multiple hydrogen bonds. One molecule could be attach to four hydrogen bonds at the same time. Cohesion is the attraction between molecules of the same substance. Water is cohesive due to hydrogen bonding. Because of this, water can form droplets and some spiders could walk on water. Adhesion is an attraction between molecules of different substances. Capilarry action is one of the forces that draw water out of a plant and up to the stems and leaves. This action involves both adhesion and cohesion.
Chemists use a measurement system called the pH scale to indicate the concentration of the H+ ions in the solution. The pH scale range from 0 to 14. Acidic solutions contain higher concentrations of H+ ions than pure water and have pH values below 7. An acid is any compound that forms H+ ions in the solution. A base is a compound that produces hydroxide ions (OH- ions) in the solution. Basic, or alkine solutions contain lower concentrations of H+ ions than pure water and have pH values above 7. There are also buffers. Buffers are weak acids or bases that can react to strong acids or bases to prevent sharp, sudden changes in pH
Water is sometimes found as part of a mixture due to it not always being pure. A mixture is a material composed of two or more elements or compounds that are physically mixed together but not chemically combined. If a bit of table salt is added into a glass of warm water, the ions from the salt breaks away and is dispersed in the water, forming a type of mixture called a solution. The table salt is the solute-the substance that is dissolved. The water is the solvent-the substance in which the solute dissolve. Mixtures of water and non-dissolved material are known as suspensions. Blood in your body is a suspension.
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