Warm upWarm up

How many paper clips will fit in the glass of How many paper clips will fit in the glass of water before the water spills over?water before the water spills over?

Hydrogen Bonds:•Weak, polar bonds.•Form rapidly and break rapidly

Example:Between water molecules

Hydrogen Bonding explains the Hydrogen Bonding explains the following properties of water:following properties of water:

1. Cohesion 2. Adhesion 3. High heat capacity 4. Evaporative cooling 5. Low density of ice 6. The ability of water to dissolve many

substances.

Water & SolutionsWater & Solutions

Water = major part of Water = major part of cellscells 70% of your body – 2/3 of molecules70% of your body – 2/3 of molecules

Water Water stores heat stores heat efficiently = heats efficiently = heats slowly and retains heat longer! Release slowly and retains heat longer! Release heat through evaporation. heat through evaporation.

MAINTAINS MAINTAINS HOMEOSTASISHOMEOSTASIS

Water & SolutionsWater & Solutions

Water bonds to itself & other substancesWater bonds to itself & other substances

COHESIONCOHESION = attraction between substances = attraction between substances of the of the SAMESAME kind. kind. Hydrogen bonds link molecules togetherHydrogen bonds link molecules together Like holding handsLike holding hands Surface Surface tensiontension – prevents surface of water from – prevents surface of water from

breaking / stretchingbreaking / stretching

The water’s surface tension allows this insect to remain supported.

http://www.realeyz.com/photo/macro/photos/leaf_drops.jpg

CohesionMolecules of the same substance are attracted to each other

•Leads to surface tension and water droplets

Water & SolutionsWater & Solutions

ADHESIONADHESION = attraction between = attraction between substances that are substances that are DIFFERENTDIFFERENT

CapillaryCapillary action = process where water action = process where water molecules move upward through narrow tube molecules move upward through narrow tube (ex: plant stem)(ex: plant stem)

• Stronger than downward gravity force.Stronger than downward gravity force.

AdhesionAttraction between molecules of different substances

Ex: glass and water

http://staff.um.edu.mt/rlib1/sm/wpe32.jpg

CapillarityAttraction that causes the surface of the liquid to rise when in contact with a solid.

Cohesion-Adhesion Theory

-As water evaporates from leaves, it tugs on the water molecules below-Cohesion and adhesion pull water up and replace missing water molecules-Water enters the roots by osmosis

www.emc.maricopa.edu/.../BioBookPLANTHORM.html

Did you ever wonder: How does water move from roots to leaves when a tree doesn’t have a heart to pump the water?

Water Dissolves Many SubstancesWater Dissolves Many Substances

SOLUTION SOLUTION = A mixture in which one or more = A mixture in which one or more substances are evenly distributed in another. substances are evenly distributed in another. (Salt Water)(Salt Water)

EX: Osmosis = movement of material/nutrients EX: Osmosis = movement of material/nutrients between cells.between cells.

Like dissolves likeLike dissolves like

Polar molecules Polar molecules dissolve easilydissolve easily Example: alcohol and Example: alcohol and

water water

LIKE DISSOLVES LIKELIKE DISSOLVES LIKE

Non-PolarNon-Polar molecules molecules do NOT dissolve well.do NOT dissolve well. EX: OIL and WATEREX: OIL and WATER

http://www.worth1000.com/entries/85500/85693bHjg_w.jpg