3.1 Water3.1 Water

IB Biology HL 1IB Biology HL 1

Mrs. PetersMrs. Peters

Fall 2013Fall 2013

WaterWater

2 Hydrogen atoms + 2 Hydrogen atoms + 1 Oxygen atom 1 Oxygen atom covalently bonded covalently bonded (polar)(polar)

Makes up 70-95% of Makes up 70-95% of living things, covers living things, covers 75% of Earth75% of Earth

DRAW and LABEL DRAW and LABEL this in your notesthis in your notes

Red: oxygen White: hydrogen

3.1.5 Cohesive Properties of Water3.1.5 Cohesive Properties of Water CohesionCohesion

created by the constant forming and reforming of hydrogen bonds between created by the constant forming and reforming of hydrogen bonds between water moleculeswater molecules

Water molecules attracted to water molecules due to polar covalent bonding Water molecules attracted to water molecules due to polar covalent bonding (+ attracted to -)(+ attracted to -)

Enables water to move against gravityEnables water to move against gravity Adhesion: Adhesion: waters ability to adhere to other things by forming hydrogen waters ability to adhere to other things by forming hydrogen

bondsbonds

3.1.4 Hydrogen Bond Formation3.1.4 Hydrogen Bond Formation Draw and label this in your notes!!!Draw and label this in your notes!!!

3.1.5 Cohesive Properties of Water3.1.5 Cohesive Properties of Water Surface TensionSurface Tension

A measure of how difficult it is to stretch or break the A measure of how difficult it is to stretch or break the surface of a liquidsurface of a liquid

Created by the cohesive property of water moleculesCreated by the cohesive property of water molecules Water has a greater surface tension than most other Water has a greater surface tension than most other

liquidsliquids

3.1.5 Thermal Properties of Water3.1.5 Thermal Properties of Water

High Specific HeatHigh Specific Heat Can absorb or give off heat energy without Can absorb or give off heat energy without

changing temperature very much due to the changing temperature very much due to the breaking and forming of hydrogen bondsbreaking and forming of hydrogen bonds• Allows organisms to maintain a constant Allows organisms to maintain a constant

temperaturetemperature• Also acts as a temperature regulator within the Also acts as a temperature regulator within the

body (blood moves warmer blood to cooler parts of body (blood moves warmer blood to cooler parts of the body)the body)

3.1.5 Thermal Properties of Water3.1.5 Thermal Properties of Water

High Heat of High Heat of Vaporization:Vaporization: transformation from liquid transformation from liquid to gasto gas Water absorbs a great deal Water absorbs a great deal

of heat when it evaporatesof heat when it evaporates Used as a cooling Used as a cooling

mechanismmechanism Creates sweat in animals Creates sweat in animals

and transpiration in plantsand transpiration in plants

Parts of SolutionsParts of Solutions

Solution:Solution: a liquid a liquid mixture of 2 or more mixture of 2 or more substancessubstances

Aqueous solution:Aqueous solution: liquid in which water liquid in which water is the solventis the solvent

Solvent:Solvent: dissolving dissolving agent of solutionsagent of solutions

Solute:Solute: substance substance being dissolvedbeing dissolved

3.1.5 Solvent Properties of Water3.1.5 Solvent Properties of Water SolventSolvent

Water’s polarity helps dissolve ions and other polar Water’s polarity helps dissolve ions and other polar substances (like dissolves like)substances (like dissolves like)

Creates an excellent medium for transporting Creates an excellent medium for transporting substances around the body substances around the body

Excellent medium for metabolic reactions to take placeExcellent 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; Blood Plasma: loading and unloading of respiratory gases;

clottingclotting

3.1.5 Solvent Properties of Water3.1.5 Solvent Properties of Water Solvent ExamplesSolvent Examples

Plants: Plants: vascular tissue carries water and vascular tissue carries water and dissolved substances dissolved substances • XylemXylem carries water and minerals from roots to leaves carries water and minerals from roots to leaves• PhloemPhloem carries dissolved sugars from leaves to stems, carries dissolved sugars from leaves to stems,

roots and flowersroots and flowers Animals: Animals: blood is the most common transport blood is the most common transport

medium, largely made up of water (blood plasma)medium, largely made up of water (blood plasma)• Transports: red blood cells, white blood cells, platelets, Transports: red blood cells, white blood cells, platelets,

dissolved molecules (glucose, amino acids, fibrinogen, dissolved molecules (glucose, amino acids, fibrinogen, hydrogencarbonate ions)hydrogencarbonate ions)

Water “Loving”Water “Loving”

HydrophilicHydrophilic: any : any substance with an substance with an attraction to waterattraction to water Substance does not Substance does not

have to dissolvehave to dissolve EX: cotton, ions, other EX: cotton, ions, other

polar substancespolar substances

Water “Non-Loving”Water “Non-Loving”

Hydrophobic:Hydrophobic: any any substance which substance which repels waterrepels water Ex: vegetable oilEx: vegetable oil

Water MoleculesWater Molecules

A water molecule can dissociate into two ions:A water molecule can dissociate into two ions: Hydrogen ion: HHydrogen ion: H++

Hydroxide ion: OHHydroxide ion: OH--

pHpH

AcidsAcids: substances which increase H: substances which increase H++ concentration of a solutionconcentration of a solution Ex: Nitric Acid: HNOEx: Nitric Acid: HNO33

BasesBases: substances which increase OH: substances which increase OH-- concentration of a solutionconcentration of a solution Ex: Sodium hydroxide: NaOHEx: Sodium hydroxide: NaOH

Buffers:Buffers: substances that minimize substances that minimize changes in pHchanges in pH

pH ScalepH Scale Range from 0-14Range from 0-14

Acids are 0-6 (0 is strong)Acids are 0-6 (0 is strong)• Strong Acids have high HStrong Acids have high H++ and and

low OH-low OH-• Weak Acids have slightly higher Weak Acids have slightly higher

HH+ + than OHthan 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 OHStrong Bases have high OH-- and and low Hlow H++

• Weak Bases have slightly higher Weak Bases have slightly higher OHOH- - than Hthan H++

• Ex: ammonia 13, sea water 8.5Ex: ammonia 13, sea water 8.5 Neutrals are at 7Neutrals are at 7

• Equal HEqual H++ and OH and OH--

• Ex: Pure water, human blood is Ex: Pure water, human blood is very closevery close

pH InvestigationpH Investigation Target: Target: Predict and determine the pH of several Predict and determine the pH of several

different household products.different household products.

Directions:Directions: Make a data tableMake a data table Record your Record your predictionprediction for pH for pH Test your product using pH test stripsTest your product using pH test strips Record the Record the actual pHactual pH Repeat for 7 other solutions.Repeat for 7 other solutions. Use the pH probe to test 4 solutions with more accuracy. Use the pH probe to test 4 solutions with more accuracy.

Record the Record the probeprobe results. results.

Compare your solution values with class mates.Compare your solution values with class mates. Answer the Analysis Questions and turn in!Answer the Analysis Questions and turn in!

pH Investigation Analysis Q’spH Investigation Analysis Q’s

1.1. Which items were acidic? Which were Which items were acidic? Which were basic?basic?

2.2. How close were your predictions?How close were your predictions?

3.3. Did any of your results differ from those Did any of your results differ from those of you classmates? Explain.of you classmates? Explain.

4.4. What is one thing you learned during this What is one thing you learned during this investigation?investigation?

3.1.6 Water Properties Review3.1.6 Water Properties ReviewProperty Reason Consequence

CohesionHydrogen 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

ThermalWater has a high boiling point (lots of energy needed to break H bonds)

Liquid at most temps life exists; medium for metabolic reactions

ThermalWater evaporates as H bonds break

acts as a coolant (sweating in animals and transpiration in plants)