Properties of Water Chapter 3

Overview of H20’s properties Resulting from hydrogen bonding: Cohesion/Adhesion/Surface tension High specific heat (temperature moderation) Density is lower as a solid than as a liquid Universal solvent Neutral pH

Cohesion/surface tension Water molecules are attracted together due to weak hydrogen bonding. Surface tension: how difficult it is to stretch or break a surface

Adhesion/Relevance Adhesion: Relevance: Water molecules are attracted to to other materials due to weak hydrogen bonding. Relevance: Poured/make waterfalls/waves, etc. (Cohesion) No energy is required for water to move up the stem of a plant (cohesion & adhesion)

Specific Heat the amount of heat energy required to bring 1 g of substance up 1 °C. Water sets the standard. Water’s = 1.

Specific Heat of Water Water’s specific heat is 1 Water heats & cools slowly because of its high specific heat due to hydrogen bonding it’s cooler by the Lake. freeze boil

http://phet.colorado.edu/en/simulation/states-of-matter

Density Liquid water’s density=1.00 g/cm3 Ice’s density is 0.92 g/cm3 As water freezes, it becomes more dense, until it reaches the highest density at 4 degrees. Then, it crystallizes & expands from 4-0 degrees, so it floats.

Universal solvent Most substances dissolve in water. Esp. ionic and polar molecules Nonpolar substances (like oil) do not dissolve in water. Solute + Solvent = Solution http://phet.colorado.edu/en/simulation/sugar-and-salt-solutions

Water is neutral Water has a pH of 7. Living things survive best in pH near 7 http://phet.colorado.edu/en/simulation/ph-scale