heat (thing)

Temperature and Heat

• The amount of heat required for a given increase in temperature in a given substance is its specific heat.
• Base unit is the calorie, one calorie is the amount of heat that will raise the temperature of one gram of water one degree Celsius
• Heat is a form if kinetic energy as applied to molecules. Moving molecules create a raise in temperature, but the bonds hold them steady. The bonds have to be broken by heat to generate a raise in temperature. This is inefficient, and creates a stable temperature for organisms.

Vaporization

• Change from a liquid to a gas.
• Water has a high heat of vaporization (at 100 degrees Celsius, it takes 540 Calories to change one gram of water into vapor.)
• Molecules break from liquid into air until the air is saturated (with humidity).
• Hydrogen bonds must be broken

Freezing

• Transition to a solid
• Density of water increases until it drops to four degrees Celsius
• All molecules form hydrogen bonds immediately and expand.
• For solid water to become liquid, 79.7 calories per gram are needed. This is its heat of fusion, and is drawn from the surroundings.
• Presence of dissolved substance lowers temperature at which water freezes.