3.1 Water 3.1 Water IB Biology HL 1 Mrs. Peters Fall 2013

Water  2 Hydrogen atoms + 1 Oxygen atom covalently bonded (polar)  Makes up 70-95% of living things, covers 75% of Earth  DRAW and LABEL this in your notes Red: oxygenWhite: hydrogen

3.1.5 Cohesive Properties of Water  Cohesion created by the constant forming and reforming of hydrogen bonds between water molecules created by the constant forming and reforming of hydrogen bonds between water molecules Water molecules attracted to water molecules due to polar covalent bonding (+ attracted to -) Water molecules attracted to water molecules due to polar covalent bonding (+ attracted to -) Enables water to move against gravity Enables water to move against gravity Adhesion: waters ability to adhere to other things by forming hydrogen bonds Adhesion: waters ability to adhere to other things by forming hydrogen bonds

3.1.4 Hydrogen Bond Formation  Draw and label this in your notes!!!

3.1.5 Cohesive Properties of Water  Surface Tension A measure of how difficult it is to stretch or break the surface of a liquid A measure of how difficult it is to stretch or break the surface of a liquid Created by the cohesive property of water molecules Created by the cohesive property of water molecules Water has a greater surface tension than most other liquids Water has a greater surface tension than most other liquids

3.1.5 Thermal Properties of Water  High Specific Heat Can absorb or give off heat energy without changing temperature very much due to the breaking and forming of hydrogen bonds Can absorb or give off heat energy without changing temperature very much due to the breaking and forming of hydrogen bonds Allows organisms to maintain a constant temperatureAllows organisms to maintain a constant temperature Also acts as a temperature regulator within the body (blood moves warmer blood to cooler parts of the body)Also acts as a temperature regulator within the body (blood moves warmer blood to cooler parts of the body)

3.1.5 Thermal Properties of Water  High Heat of Vaporization: transformation from liquid to gas Water absorbs a great deal of heat when it evaporates Water absorbs a great deal of heat when it evaporates Used as a cooling mechanism Used as a cooling mechanism Creates sweat in animals and transpiration in plants Creates sweat in animals and transpiration in plants

Parts of Solutions  Solution: a liquid mixture of 2 or more substances  Aqueous solution: liquid in which water is the solvent  Solvent: dissolving agent of solutions  Solute: substance being dissolved

3.1.5 Solvent Properties of Water  Solvent Water’s polarity helps dissolve ions and other polar substances (like dissolves like) Water’s polarity helps dissolve ions and other polar substances (like dissolves like) Creates an excellent medium for transporting substances around the body Creates an excellent medium for transporting substances around the body Excellent medium for metabolic reactions to take place Excellent medium for metabolic reactions to take place Cytoplasm: glycolysis, protein synthesis reactionsCytoplasm: glycolysis, protein synthesis reactions Nucleoplasm: DNA replication, transcriptionNucleoplasm: DNA replication, transcription Stroma: light reactions of photosynthesisStroma: light reactions of photosynthesis Blood Plasma: loading and unloading of respiratory gases; clottingBlood Plasma: loading and unloading of respiratory gases; clotting

3.1.5 Solvent Properties of Water  Solvent Examples Plants: vascular tissue carries water and dissolved substances Plants: vascular tissue carries water and dissolved substances Xylem carries water and minerals from roots to leavesXylem carries water and minerals from roots to leaves Phloem carries dissolved sugars from leaves to stems, roots and flowersPhloem carries dissolved sugars from leaves to stems, roots and flowers Animals: blood is the most common transport medium, largely made up of water (blood plasma) Animals: blood is the most common transport medium, largely made up of water (blood plasma) Transports: red blood cells, white blood cells, platelets, dissolved molecules (glucose, amino acids, fibrinogen, hydrogencarbonate ions)Transports: red blood cells, white blood cells, platelets, dissolved molecules (glucose, amino acids, fibrinogen, hydrogencarbonate ions)

Water “Loving”  Hydrophilic: any substance with an attraction to water Substance does not have to dissolve Substance does not have to dissolve EX: cotton, ions, other polar substances EX: cotton, ions, other polar substances

Water “Non-Loving”  Hydrophobic: any substance which repels water Ex: vegetable oil

Water Molecules  A water molecule can dissociate into two ions: Hydrogen ion: H + Hydrogen ion: H + Hydroxide ion: OH - Hydroxide ion: OH -

pH  Acids: substances which increase H + concentration of a solution Ex: Nitric Acid: HNO 3 Ex: Nitric Acid: HNO 3  Bases: substances which increase OH - concentration of a solution Ex: Sodium hydroxide: NaOH Ex: Sodium hydroxide: NaOH  Buffers: substances that minimize changes in pH

pH Scale  Range from 0-14 Acids are 0-6 (0 is strong) Acids are 0-6 (0 is strong) Strong Acids have high H + and low OH-Strong Acids have high H + and low OH- Weak Acids have slightly higher H + than OH -Weak Acids have slightly higher H + than OH - Ex: gastric juice 2, urine 6Ex: gastric juice 2, urine 6 Bases are 8-14 (14 is strong) Bases are 8-14 (14 is strong) Strong Bases have high OH - and low H +Strong Bases have high OH - and low H + Weak Bases have slightly higher OH - than H +Weak Bases have slightly higher OH - than H + Ex: ammonia 13, sea water 8.5Ex: ammonia 13, sea water 8.5 Neutrals are at 7 Neutrals are at 7 Equal H + and OH -Equal H + and OH - Ex: Pure water, human blood is very closeEx: Pure water, human blood is very close

pH Investigation  Target: Predict and determine the pH of several different household products.  Directions: Make a data table Make a data table Record your prediction for pH Record your prediction for pH Test your product using pH test strips Test your product using pH test strips Record the actual pH Record the actual pH Repeat for 7 other solutions. Repeat for 7 other solutions. Use the pH probe to test 4 solutions with more accuracy. Record the probe results. Use the pH probe to test 4 solutions with more accuracy. Record the probe results.  Compare your solution values with class mates.  Answer the Analysis Questions and turn in!

pH Investigation Analysis Q’s 1. Which items were acidic? Which were basic? 2. How close were your predictions? 3. Did any of your results differ from those of you classmates? Explain. 4. What is one thing you learned during this investigation?

3.1.6 Water Properties Review PropertyReasonConsequence Cohesion Hydrogen bonds hold water molecules together Water can travel in continuous columns; act as a transport medium Solvent Polar molecules of water can interact with other polar molecules Able to dissolve ions and large molecules with polar side chains; acts as an excellent transport medium and medium for metabolic reactions Thermal Water has a high heat capacity (lots of energy needed to break H bonds and change temp) Organism temp changes slowly; body fluid (blood) transports heat throughout Thermal Water has a high boiling point (lots of energy needed to break H bonds) Liquid at most temps life exists; medium for metabolic reactions Thermal Water evaporates as H bonds break acts as a coolant (sweating in animals and transpiration in plants)