Honors BiologyHonors Biology

WATER AND WATER AND pH NotespH Notes

Characteristics of WaterCharacteristics of Water http://www.allaboutwater.org/water-fachttp://www.allaboutwater.org/water-fac

ts.htmlts.html Cool water facts. Cool water facts.

A single water molecule is held A single water molecule is held together by polar covalent bonds, BUT, together by polar covalent bonds, BUT, if you want to attach a bunch of water if you want to attach a bunch of water molecules together, (Which is normally molecules together, (Which is normally what we think of when we hear the what we think of when we hear the word water), we need Hydrogen Bonds.word water), we need Hydrogen Bonds.

Molecule ImageMolecule Image Dotted lines are Dotted lines are

the Hydrogen the Hydrogen Bonds Bonds

Key Properties of WaterKey Properties of Water (table 3.2) (table 3.2)

A) Heat storageA) Heat storage B) Ice FormationB) Ice Formation C) High Heat of VaporizationC) High Heat of Vaporization D) Cohesion/adhesionD) Cohesion/adhesion E) Hydrophobic/hydrophilicE) Hydrophobic/hydrophilic

A)A) Heat StorageHeat Storage

Co py rig ht © The McGr aw-H ill Co mpa nies, Inc. Perm issio n re quir ed for r epro duc tio n or d ispla y

When talking about temperature, we are really When talking about temperature, we are really talking about how fast molecules are moving. IF talking about how fast molecules are moving. IF they move fast, the temperature is high, if they they move fast, the temperature is high, if they move slowly, the temperature is low.move slowly, the temperature is low.

Large input of thermal energy is required to Large input of thermal energy is required to disrupt the organization of liquid waterdisrupt the organization of liquid water

This minimizes temperature changesThis minimizes temperature changes Water heats up and cools down VERY slowly Water heats up and cools down VERY slowly

because you first need to break the hydrogen because you first need to break the hydrogen bonds.bonds.

Biological importance of Biological importance of heat storageheat storage

Your body doesn’t immediately boil Your body doesn’t immediately boil when you step outside in July.when you step outside in July.

You can swim in your swimming pools You can swim in your swimming pools in October and not freeze, but you in October and not freeze, but you can’t jump in your pool during June can’t jump in your pool during June before the pool heats up enough.before the pool heats up enough.

What other things can you think of?What other things can you think of?

B) Ice FormationB) Ice Formation Low temperature means the H-Low temperature means the H-

Bonds are pretty stable, but they Bonds are pretty stable, but they may take on a cool property. They may take on a cool property. They arrange themselves in a way that arrange themselves in a way that makes ice LESS dense as a solid. makes ice LESS dense as a solid. Most other liquids react the Most other liquids react the opposite when they get colder.opposite when they get colder.

Biological Importance of Biological Importance of Ice FormationIce Formation

Ice floats!Ice floats! Oceans/bodies of water freeze Oceans/bodies of water freeze

from the top down. Creates a nice from the top down. Creates a nice insulated layer so that life can still insulated layer so that life can still exist in the ocean.exist in the ocean.

Any other reasons you can think Any other reasons you can think of?of?

C) High heat of C) High heat of vaporizationvaporization

To Vaporize means to turn into a To Vaporize means to turn into a gas. What does it take for liquid gas. What does it take for liquid water to do this?water to do this?

Move fast enough so that the H-Move fast enough so that the H-bonds can break. When the H-bonds can break. When the H-Bond is broken, it carries with it a Bond is broken, it carries with it a great deal of heat!great deal of heat!

Biological importance …..Biological importance ….. Sweating cools Sweating cools

you off! When you you off! When you sweat, the fast sweat, the fast moving water is moving water is literally leaving literally leaving your body… the your body… the molecules left molecules left behind are behind are moving slowly so moving slowly so you feel cooler.you feel cooler.

D) Cohesion/AdhesionD) Cohesion/Adhesion Because of the H-Bonds, water can Because of the H-Bonds, water can

stick to other water molecules and stick to other water molecules and to other objects. (Examples: to other objects. (Examples: Capillary Action and Surface Capillary Action and Surface Tension)Tension)

Biological Importance of Biological Importance of Cohesion/AdhesionCohesion/Adhesion

http://www.youtube.com/watch?http://www.youtube.com/watch?v=CT4pURpXkbYv=CT4pURpXkbY

Towels can actually dry you off Towels can actually dry you off when you get out of the shower.when you get out of the shower.

Straws workStraws work Any other ideas?Any other ideas?

Surface tensionSurface tension Molecules inside a Molecules inside a

water droplet are water droplet are attracted in all attracted in all directions. Drops directions. Drops on the surface are on the surface are attracted to the attracted to the sides and inward.sides and inward.

Cohesion VS Cohesion VS AdhesionAdhesion

The mutual attractive The mutual attractive forceforce that exists between like that exists between like molecules of a particular liquid is called cohesion. molecules of a particular liquid is called cohesion.

This force is responsible for holding a raindrop This force is responsible for holding a raindrop together as a single unit. Cohesion produces the together as a single unit. Cohesion produces the

phenomenon known as phenomenon known as surface tensionsurface tension, which may , which may allow objects that are more dense than the liquid to allow objects that are more dense than the liquid to

be supported on the surface of the liquid without be supported on the surface of the liquid without sinking. When an attractive force exists between two sinking. When an attractive force exists between two

unlike materials, such as a liquid and a solid unlike materials, such as a liquid and a solid container, the attractive force is known as adhesion. container, the attractive force is known as adhesion.

Adhesion is the force that causes Adhesion is the force that causes waterwater to stick to the to stick to the inside of a inside of a glassglass

Capillary ActionCapillary Action Capillary actionCapillary action, or , or capillaritycapillarity, , is the ability of a liquid to flow is the ability of a liquid to flow against gravity where liquid against gravity where liquid spontaneously rises in a narrow spontaneously rises in a narrow space such as a thin tube, or in space such as a thin tube, or in porous materials such as paper or porous materials such as paper or in some non-porous materials such in some non-porous materials such as liquified carbon fibre. This as liquified carbon fibre. This effect can cause liquids to flow effect can cause liquids to flow against the force of gravity or the against the force of gravity or the magnetic field induction. magnetic field induction.

E) Hydrophobic and E) Hydrophobic and HydrophilicHydrophilic

The term Hydrophobic means “water The term Hydrophobic means “water fearing”.fearing”.

The term Hydrophilic means “water The term Hydrophilic means “water loving”. loving”.

The terms really mean the ability or The terms really mean the ability or inability to DISSOLVE in water. Like inability to DISSOLVE in water. Like dissolves like. dissolves like.

Since water is polar, any polar molecule Since water is polar, any polar molecule can dissolve in water.can dissolve in water.

Biologic ImportanceBiologic Importance Most of our blood is made up of Most of our blood is made up of

water, so nutrients can be dissolved water, so nutrients can be dissolved in our blood and transported in our blood and transported through out the body without through out the body without needing to be big and clunky and needing to be big and clunky and blocking up the veins and arteries.blocking up the veins and arteries.

Our skin must be hydrophobic since Our skin must be hydrophobic since we don’t dissolve when it rains.we don’t dissolve when it rains.

Structure of Water videoStructure of Water video http://www.youtube.com/watch?http://www.youtube.com/watch?

v=KiZJOTt3Dl0&feature=relatedv=KiZJOTt3Dl0&feature=related

pHpH Reminder: Water is held together by Reminder: Water is held together by

___________________ bonds.___________________ bonds. These are relatively __________ bonds.These are relatively __________ bonds. These bonds are constantly _________ These bonds are constantly _________

and _____________.and _____________. When water breaks apart, there is a When water breaks apart, there is a

way to represent this using chemical way to represent this using chemical equations. (Dissociation of water)equations. (Dissociation of water)

Dissociation of waterDissociation of water IF you measure how IF you measure how

much is H= you much is H= you would find the would find the concentration to be concentration to be 1/10,000,000.1/10,000,000.

Use exponents 10 ^ Use exponents 10 ^ -7-7

[ ] brackets mean [ ] brackets mean “concentration” so “concentration” so [H+] is translated [H+] is translated to concentration of to concentration of HydrogenHydrogen

[H+] and pH values are [H+] and pH values are opposite!opposite!

A) if pH is low, what about the A) if pH is low, what about the [H+] ?[H+] ?

B) if the pH is high, what about B) if the pH is high, what about the [H+]?the [H+]?

Acids vs BasesAcids vs Bases Acids: Anything that dissolves in Acids: Anything that dissolves in

water and adds H+. OH NO! water and adds H+. OH NO! IMBALANCE!IMBALANCE!

Bases: Anything that dissolves in Bases: Anything that dissolves in water and combines with H+. Not water and combines with H+. Not necessarily bad, but now there is an necessarily bad, but now there is an imbalance with the OH- ion.imbalance with the OH- ion.

THEY NEED TO STAY BALANCED!THEY NEED TO STAY BALANCED!

BUFFERSBUFFERS What would a buffer do if pH falls?What would a buffer do if pH falls? What would a buffer do if pH rises?What would a buffer do if pH rises?