Chapter 2
2.3 Properties of Water:
Water has a high heat capacity
A calorie is the amount of heat energy required to raise 1g of water by 1C
The many hydrogen bonds that link water molecules together help water absorb a lot of heat without changing temperature.
Water has a high heat of vaporization
It takes 540 calories of heat energy to convert 1g of water into its gaseous state
Water has a high heat of vaporization because of the many hydrogen bonds that would have to be broken to boil water.
Water is a solvent
Due to its polarity, water is a good solvent as it dissolves a great number of substances. For example, if NaCl were to be in water the negative ends of H2O would be attracted to Na and the positive ends of H2O would be attracted to Cl. This would cause NaCl to separate or dissociate
Hydrophilic, molecules that attract water
Hydrophobic, molecules that cannot attract water Water is cohesive and adhesive
Cohesion is shown through water because it flows freely as one without breaking apart. This is due to its hydrogen bonds
Adhesion is shown because water adheres (sticks) to polar surfaces due to its positive and negative poles.
Water has high surface tension
The higher force between molecules in water, the higher surface tension
As with cohesion, hydrogen bonds help water have a high surface tension.
Frozen water is less dense than liquid water
As liquid water cools, molecules become closer together. As liquid water turns into ice below zero, molecules form a regular lattice that is rigid and spaced out causing it to expand. This causes ice to be less dense than liquid water.
Acids & Bases
Acidic solutions release hydrogen ions (H+) when dissociated in water.
Bases take up hydrogen ions (H+) or release hydroxide ions (OH-)
Buffers and pH
Buffers are a substance that keep pH within normal limits