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Should we control a chemical that:
Should we control a chemical that:
Causes excessive sweating and vomiting.
Is a major component in acid rain.
Can cause severe burns in its gaseous state.
Causes excessive sweating and vomiting.
Is a major component in acid rain.
Can cause severe burns in its gaseous state.
Accidental inhalation can kill you.
Contributes to erosion.
Decreases the effectiveness of car brakes.
Has been found in tumors of terminal cancer patients.
Accidental inhalation can kill you.
Contributes to erosion.
Decreases the effectiveness of car brakes.
Has been found in tumors of terminal cancer patients.
What is the chemical?What is the chemical?
Dihydrogen monoxide
Otherwise known as H2O
Dihydrogen monoxide
Otherwise known as H2O
Chapter 3Water and the Fitness of
the Environment
Chapter 3Water and the Fitness of
the Environment
Question?Question?
What molecule Is the most common In living Cells?
Water - most cells are 70 - 95% water.
What molecule Is the most common In living Cells?
Water - most cells are 70 - 95% water.
Properties Of WaterProperties Of Water
Be ready and able to discuss several of the following properties.
Focus on definitions and examples.Review water structure and
Hydrogen bonds from Chapter 2.
Be ready and able to discuss several of the following properties.
Focus on definitions and examples.Review water structure and
Hydrogen bonds from Chapter 2.
Liquid Water Is CohesiveLiquid Water Is Cohesive
Water sticks to water.Why? Because the polarity of water
results in hydrogen bonding.
Water sticks to water.Why? Because the polarity of water
results in hydrogen bonding.
Liquid Water is AdhesiveLiquid Water is Adhesive
Water sticks to other molecules.Why? Hydrogen bonding.
Water sticks to other molecules.Why? Hydrogen bonding.
Water transport in trees uses Cohesion and Adhesion
Water transport in trees uses Cohesion and Adhesion
Water Has A High Surface Tension
Water Has A High Surface Tension
The surface of water is difficult to stretch or break.
Why? Hydrogen bonding.
The surface of water is difficult to stretch or break.
Why? Hydrogen bonding.
Water Has A High Specific Heat
Water Has A High Specific Heat
Specific Heat - the amount of heat needed to raise 1 g of the substance 1 degree C.
Why? Hydrogen bonding.
Specific Heat - the amount of heat needed to raise 1 g of the substance 1 degree C.
Why? Hydrogen bonding.
HeatHeat
Total quantity of kinetic energy due to molecular motion.
Total quantity of kinetic energy due to molecular motion.
TemperatureTemperature
Measures the average speed of the molecules.
Measures the average speed of the molecules.
Celsius ScaleCelsius Scale
Will be used for most of our temperature measurements.
O oC - water freezes100 oC - water boils37 oC - human body
Will be used for most of our temperature measurements.
O oC - water freezes100 oC - water boils37 oC - human body
Water Stabilizes Temperature
Water Stabilizes Temperature
Water can absorb and store a huge amount of heat from the sun.
Result - climate moderationResult - organisms are able to
survive temperature changes.
Water can absorb and store a huge amount of heat from the sun.
Result - climate moderationResult - organisms are able to
survive temperature changes.
Water Has A High Heat Of Vaporization
Water Has A High Heat Of Vaporization
Heat of Vaporization: the quantity of heat a liquid must absorb for 1g of it to convert to a gaseous state.
Heat of Vaporization: the quantity of heat a liquid must absorb for 1g of it to convert to a gaseous state.
Result:Result:
Water cools organisms from excessive heat buildup.
Why? Hydrogen bonding
Water cools organisms from excessive heat buildup.
Why? Hydrogen bonding
Water Expands When It Freezes
Water Expands When It Freezes
The distance between water molecules INCREASES from the liquid to the solid form.
Why?Hydrogen bonding
The distance between water molecules INCREASES from the liquid to the solid form.
Why?Hydrogen bonding
Solids and LiquidsSolids and Liquids
Water Benzene
Floats Sinks
Solid Liquid Gas
States of Matter
ResultResultAquatic life can live under ice.Aquatic life can live under ice.
Water Is A Versatile Solvent
Water Is A Versatile Solvent
Water will form a solution with many materials.
Why? Hydrogen bonding
Water will form a solution with many materials.
Why? Hydrogen bonding
SolutionSolution
Homogeneous mixture of two or more substances.
Homogeneous mixture of two or more substances.
SolventSolvent
The dissolving agent.The material in the greater
quantity.
The dissolving agent.The material in the greater
quantity.
SoluteSolute
The substance that is dissolved.The material in the lesser quantity.
The substance that is dissolved.The material in the lesser quantity.
Hydrophilic MaterialsHydrophilic Materials
Materials that dissolve in water.Hydro - waterphilic - to like or loveHave ionic or polar regions (polar
covalent bonds) on their molecules for H+ bonds.
Materials that dissolve in water.Hydro - waterphilic - to like or loveHave ionic or polar regions (polar
covalent bonds) on their molecules for H+ bonds.
HydrophobicHydrophobic
Materials that repel water.Hydro - waterphobic - to fearHave non-polar covalent bonds. Ex
- lipids.
Materials that repel water.Hydro - waterphobic - to fearHave non-polar covalent bonds. Ex
- lipids.
Solution ConcentrationSolution Concentration
Usually based on Molarity.Molarity - the number of moles of
solute per liter of solution.
Usually based on Molarity.Molarity - the number of moles of
solute per liter of solution.
MolesMoles
The molecular weight of a substance in grams.
One Avogadro’s number of molecules.
6.02 X 1023
The molecular weight of a substance in grams.
One Avogadro’s number of molecules.
6.02 X 1023
One Mole of eachOne Mole of each
Sulfur
Sugar
Copper Sulfate
Mercury Oxide
Copper
Sodium Chloride
CommentComment
AP Biology students should be able to calculate solutions in Molarity.
AP Biology students should be able to calculate solutions in Molarity.
Dissociation of WaterDissociation of WaterWater can sometimes split into two
ions.
In pure water the concentration of
each ion is 10-7 M
Water can sometimes split into two ions.
In pure water the concentration of
each ion is 10-7 M
Adding certain solutes disrupts the balance between the two ions.
The two ions are very reactive and can drastically affect a cell.
Adding certain solutes disrupts the balance between the two ions.
The two ions are very reactive and can drastically affect a cell.
AcidsAcids
Materials that can release H+
Example: HCl
HCl H+ + Cl-
Materials that can release H+
Example: HCl
HCl H+ + Cl-
Acid RainAcid Rain
Acid RainAcid Rain
BasesBases
Materials that can absorb H+
Often reduce H+ by producing OH-
Example: NaOH
NaOH Na+ + OH-
Materials that can absorb H+
Often reduce H+ by producing OH-
Example: NaOH
NaOH Na+ + OH-
NeutralsNeutrals
Materials that are neither acids nor bases.
Materials that are neither acids nor bases.
pH ScalepH Scale
A logarithmic scale for showing H+ concentration
pH = - log [H+]
A logarithmic scale for showing H+ concentration
pH = - log [H+]
pH ScalepH Scale
Example:Example:
For a neutral solution:[H+] is 10-7
or - log 10-7 or - (-7)or 7
For a neutral solution:[H+] is 10-7
or - log 10-7 or - (-7)or 7
Acids: pH <7 etc.
Bases: pH >7 etc.
Each pH unit is a 10x change in H+
Acids: pH <7 etc.
Bases: pH >7 etc.
Each pH unit is a 10x change in H+
CommentComment
[H+] + [OH-] = 14Therefore, if you know the
concentration of one ion, you can easily calculate the other.
[H+] + [OH-] = 14Therefore, if you know the
concentration of one ion, you can easily calculate the other.
BuffersBuffers
Materials that have both acid and base properties.
Resist pH shifts.Cells and other biological solutions
often contain buffers to prevent damage.
Materials that have both acid and base properties.
Resist pH shifts.Cells and other biological solutions
often contain buffers to prevent damage.
SummarySummary
Be able to discuss the properties of water.
Be able to measure solution concentrations in Molarity.
Be able to work pH scale questions.
Be able to discuss the properties of water.
Be able to measure solution concentrations in Molarity.
Be able to work pH scale questions.
