Guided Lecture Notes
Chapter 2 – Water and Life
1. What are the four emergent properties of water and how do they contribute to life on
Earth?
-cohesive behavior; hydrogen bonding keeps molecules of water close together.
In liquid form the arrangement of molecules in water is constantly changing at
any given time many molecules of water are linked together by hydrogen bonds
this helps give water its structure.
Cohesion helps the transport of water against gravity in plants .
adhesion is an attraction between different substances (ex: water and plant walls) this helps
counter the downward pull on the water.
- surface tension ; is a measure of how hard it is to break the surface of a liquid.
surface tension is related to cohesion.
ability to moderate temperature; Water absorbs heat from warmer air and releases stored
heat to cooler air. Water can absorb or release a large amount of heat with only a slight change
in its own temperature.
-Kinetic energy is the energy of motion
-Heat is a measure of the total amount of kinetic energy due to molecular motion
-Temperature measures the intensity of heat due to the average kinetic energy of
molecules
-The Celsius scale is a measure of temperature using Celsius degrees (°C)
-A calorie (cal) is the amount of heat required to raise the temperature of 1 g of water by
1°C
-The joule(J) - is another unit of energy where 1 J = 0.239 cal or 1 cal = 4.184 J
-The specific heat of a substance is the amount of heat that must be absorbed or lost for
1 g of that substance to change its temperature by 1ºC
- The specific heat of water is 1 cal/g/ºC
- Water resists changing its temperature because of its high specific heat\
- Water’s high specific heat can be traced to hydrogen bonding
- Heat is absorbed when hydrogen bonds break
- Heat is released when hydrogen bonds form
- The high specific heat of water minimizes temperature fluctuations to within limits that
permit life
- Evaporative cooling of water helps stabilize temperatures in organisms and bodies of
water
