15
2.2 Properties of Water Bell Ringer: • On page 39 Answer # 1 and #3 • You will turn in your bell work today! 9-21-12 • When you finish look over terms.
2.2 Properties of Water
Bell Ringer:
• On page 39 Answer # 1 and #3
• You will turn in your bell work today! 9-21-12• When you finish look over terms.
2.2 Properties of Water
KEY CONCEPTWater’s unique properties allow life to exist on Earth.
2.2 Properties of Water
OHH
_
++
Life depends on hydrogen bonds in water.
• Water is a polar molecule.– Polar molecules have slightly charged regions.
- Due to uneven pull of e-
– Nonpolar molecules do not have charged regions.– Hydrogen bonds form between slightly positive hydrogen atoms and slightly negative atoms.
2.2 Properties of WaterBell Ringer- Fill in the following chart
Have your homework on your desk! Friday’s date is 9-28-12
Charge?
Example
What do the electrons do?
Nonpolar Covalent Polar CovalentIonicType of Bond:
2.2 Properties of Water
Bell Ringer:
• On pg 39 answer #3,4,and 5
2.2 Properties of Water
• Hydrogen bonds are responsible for three important properties of water.– High specific heat
– must absorb more heat to change temperature.– Regulates cell temperature
– Cohesion– Causes surface tension &
water beading– Adhesion
– Helps roots carry water
2.2 Properties of Water
“How are hydrogen bonds silmilar to ionic bonds?”
2.2 Properties of WaterMany compounds dissolve in water.
• A solution is formed when one substance dissolves in another.– A solution is a homogeneous mixture.– Solvents dissolve other substances.– Solutes dissolve in a solvent.
solution
2.2 Properties of Water
• “Like dissolves like.”
– Polar solvents dissolve polar solutes.– Nonpolar solvents dissolve nonpolar solutes.– Polar substances and nonpolar substances generally
remain separate.
2.2 Properties of Water
“What are solvent & solutes in beverages that you drink?”
2.2 Properties of WaterSome compounds form acids or bases.
• An acid releases a hydrogen ion when it dissolves in water.– high H+ concentration– pH less than 7
more acidic
stomach acid pH between 1 and 3
2.2 Properties of Water
• A base removes hydrogen ions from a solution.
– low H+ concentration– pH greater than 7
bile pH between 8 and 9
more basic
2.2 Properties of Water
• A neutral solution has a pH of 7.
pure water pH 7
2.2 Properties of Water
• Most organisms need to keep their pH in a narrow range.– Human blood pH=7.4– Bile pH=8-9– Stomach acid 1-3– Azalea plants need soil at 4.5– Large changes are deadly
2.2 Properties of Water
Bell Work: Write in notes as well!
“Cells have higher H+ concentration than blood. Which has a higher pH?”
