Chapter 3: Water and the Fitness of the Environment Makes life on Earth possible Makes life on Earth possible ¾ of Earth’s surface ¾ of Earth’s surface % of cells mass % of cells mass Cytoplasm and blood are mostly water Cytoplasm and blood are mostly water Small, simple molecule Small, simple molecule Very common (occurrence) Very common (occurrence) Very uncommon (chemistry) Very uncommon (chemistry) Several unique properties *** know these *** Several unique properties *** know these ***

Polar covalent molecule 2 hydrogen and 1 oxygen 2 hydrogen and 1 oxygen Mass of 18 Mass of 18 Strong zones of partial positive and partial negative – “poles” Strong zones of partial positive and partial negative – “poles” Cooperates in MANY hydrogen bonds Cooperates in MANY hydrogen bonds Results in emergent properties Results in emergent properties –Conditions or traits that appear (emerge) because of the structure or relationships between components. –Ex: molecules have different properties than elements and a forest has different properties than a tree.

Cohesion and Adhesion Surface tension Surface tension Cohesion means water “sticks” to other water molecules….. “beads” Cohesion means water “sticks” to other water molecules….. “beads” –This helps keep water liquid, the form we need most as living organisms (cytoplasm to oceans) Adhesion means that water “sticks” to other substances Adhesion means that water “sticks” to other substances –Meniscus in graduated cylinder –Xylem and phloem in plant stems –Necessary for PHOTOSYNTHESIS

Moderates temperature Heat => measure of total kinetic energy Heat => measure of total kinetic energy Temperature=> intensity of heat due to average kinetic energy Temperature=> intensity of heat due to average kinetic energy Kilocalorie =>food cal., 1000 calories Kilocalorie =>food cal., 1000 calories Calorie => amt of heat required to raise one gram of water by one degree Celsius Calorie => amt of heat required to raise one gram of water by one degree Celsius Specific heat => amt of heat that must be gained or lost in order to heat or cool one gram of a substance by 1 degree Celsius Specific heat => amt of heat that must be gained or lost in order to heat or cool one gram of a substance by 1 degree Celsius Water has relatively high specific heat Water has relatively high specific heat

Specific Heat Because water has a high specific heat compared to other molecules its size Because water has a high specific heat compared to other molecules its size –It take a long time to change temp. –Lake stays warm in fall –Ocean temperatures don’t vary much –Body temp stays steady

Evaporative Cooling Heat of vaporization => quantity of heat required to convert 1 gram of substance from liquid to gas Heat of vaporization => quantity of heat required to convert 1 gram of substance from liquid to gas Evaporation of sweat (water) takes out a lot of body’s heat (lowers temperature) Evaporation of sweat (water) takes out a lot of body’s heat (lowers temperature) –Hottest molecules closest to phase change, lowers overall kinetic energy…. –Sweat, drool, pant, large ears, capillaries, etc

Ice Floats Liquid water has H bonds that hold water in a very density collection Liquid water has H bonds that hold water in a very density collection Solid water (ice) actually has longer bonds, liquid water’s bonds are further apart, less dense Solid water (ice) actually has longer bonds, liquid water’s bonds are further apart, less dense Floating ice Floating ice –Doesn’t overflow –Acts as insulation –Allows for bottom to stay liquid –Lake can “melt” completely in the summer –Weather because of cold polar water and warm equatorial waters … flow and currents

Solvent of Life Solution =>homogenous liquid mixture of two or more substances Solution =>homogenous liquid mixture of two or more substances Solute=> what is dissolved, solid, smaller amt. Solute=> what is dissolved, solid, smaller amt. Solvent=> what did the dissolving, liquid, larger amt. Solvent=> what did the dissolving, liquid, larger amt. Aqueous solution => solution where solvent is water Aqueous solution => solution where solvent is water Very common in nature Very common in nature

Solutions Blood is a solution that carries dissolved nutrients, oxygen and waste to and from cells Blood is a solution that carries dissolved nutrients, oxygen and waste to and from cells Cytoplasm ( cytosol ) is a solution that is mostly water and is the site of all chemical reactions in cells Cytoplasm ( cytosol ) is a solution that is mostly water and is the site of all chemical reactions in cells Most biochemistry is carried out in aqueous solutions Most biochemistry is carried out in aqueous solutions

Solutions cont. Hydrophilic =>water loving Hydrophilic =>water loving Hydrophobic => water fearing Hydrophobic => water fearing Molarity => number of moles per liter of solution (mole is atomic mass in grams) Molarity => number of moles per liter of solution (mole is atomic mass in grams) –** Be able to calculate molar solutions ** Dissociation=> degree to which a substance separates when in solution. Dissociation=> degree to which a substance separates when in solution. Water separates into H + and OH - Water separates into H + and OH - Acid => has more H + than OH - available Acid => has more H + than OH - available Base => has more OH - than H + available Base => has more OH - than H + available

pH pH is the negative log of the H+ concentration and is a measure of how much the water has dissociated and how much H+ is available pH is the negative log of the H+ concentration and is a measure of how much the water has dissociated and how much H+ is available Organisms are very sensitive to pH ranges. Organisms are very sensitive to pH ranges. Some acids include gastic acid, lemon juice, soda, coffee, rain(6) and urine (6) Some acids include gastic acid, lemon juice, soda, coffee, rain(6) and urine (6) Pure water should be neutral (7) Pure water should be neutral (7) Some bases would include sea water (8), blood (7.4), Tums, ammonia/bleach and many cleaners Some bases would include sea water (8), blood (7.4), Tums, ammonia/bleach and many cleaners

Acid Precipitation Can be in any format (rain or snow) Can be in any format (rain or snow) Also exists as exhaust and run off Also exists as exhaust and run off S and N in atmosphere bond to water creating acids S and N in atmosphere bond to water creating acids Changing pH of lakes or oceans is harmful to plant and animal life there Changing pH of lakes or oceans is harmful to plant and animal life there Changing pH of soil changes the charge and availability of ions and nutrients that are used by plants Changing pH of soil changes the charge and availability of ions and nutrients that are used by plants Both can have impacts on food webs and our food/water/oxygen supply – Constant fertilizer use can change soil ph (acidic) reverse with “lime” which is calcium carbonate Both can have impacts on food webs and our food/water/oxygen supply – Constant fertilizer use can change soil ph (acidic) reverse with “lime” which is calcium carbonate