Download File

Let’s Talk About Evil, Mean, Nasty Water
So what was the conversation like between H & O?
H
+
O
• H2O is polar – there is an uneven distribution of
e-’s
• H2O is polar covalent which means it kind of shares e-’s
… the e-’s remain mostly with O
– H only gets them a small part of the time
Like Dissolves Like
• If you add a polar substance to a polar liquid,
they will mix.
• If you add a non-polar substance to a polar
liquid, they will not mix.
– Ex. Water and oil
A little chemistry humor
H-bonds Make H2O Stubborn
b/c of its molecular structure, H2O is stubborn &
will not be broken apart easily; this characteristic is due
to
H-bonds
H-bond – the H from one H2O molecule & the
O from another H2O molecule are
attracted to each other
attraction is weaker than an ionic bond, but
it does cause some unique properties
Properties of Water
• cohesion – attractions between the same molecule
– ex: this is why if H2O is spilled it will remain together in a puddle
• adhesion – the attraction between molecules of a diff substance
– ex: this is why H2O is able to travel up tubes like straws (= capillary action)
and the xylem & phloem of plants (= transpiration)
• solid form is lighter (less dense) than the liquid form
– ex: ice floats
• has a high specific heat (specific heat = the amount of E it takes to
change 1 g of H2O, 1º)
• has a high surface tension
– ex: see water glider pic in book
H2O is a Snob!
• notoriously snobbish, H2O only mixes w/
molecules that are like itself…
What molecules are like H2O ?
• for ex: when H2O sees NaCl, what does it want to
do?
NaCl + H2O 
H2O is the ultimate hater!
Putting Stuff Together
• mixture (mix) – 2 or more substances combined
together but not chemically combined.
ex: cereal
• solution (soln) – the substances involved are
chemically combined.
ex: V8 Juice
solute =
solvent =
H2O is the universal solvent!
• suspensions – materials that do not dissolve when
placed in H2O, but separate into small pieces
– ex. Wishbone salad dressing
Day 2
WATER LAB
Acids & Bases
• remember H2O only mixes w/ cmpds that are
like itself……who are those cmpds?
____________________________
• H2O is in a constant state of disassociation
meaning it goes back & forth btw being a whole
molec & ions…
hydrogen ion
H2O
H+ + OHhydroxide ion
pH = potential hydrogens
pH is a measure of the # or conc of H+ ions in soln…
...THINK about that for a second…
the pH scale is based on the power of 10
• Any solution w/ a pH lower than 7 has more
hydrogen ions than hydroxide ions in solution.
• Any solution with a pH higher than 7 has fewer hydrogen
ions than hydroxide ions in solution.
• & since the scale is based on the power of 10…
a pH of 2 indicates ten times fewer H+ than a pH
of 1, pH 3 has ten times fewer H+ than pH 2 & one
hundred times fewer H+ than pH 1……
neutral
1
ACIDS = more H+
7
BASES = more OH14
• acid + H2O  H+ + salt
ex: HCl + H2O  H+ + Cl• base + H2O  OH- + salt
ex: NaOH + H2O  OH- + Na+
Practice
Use your knowledge of H2O. If the following substances
were dissolved in H2O, would they be considered acids or
bases? The answers, and their common names will be
revealed on the next slide.
1) HCl
2) H2SO4
3) HNO3
4) H2CO3
5) NaOH
6) Ca(OH)2
7) NH4OH
8) Mg(OH)2
Practice Answers
1) Hydrochloric acid (HCl) in gastric juice
2) Sulphuric acid (H2SO4)
3) Nitric acid (HNO3)
4) Carbonic acid in softdrink (H2CO3)
5) Sodium hydroxide (NaOH) or caustic soda
6) Calcium hydroxide ( Ca(OH)2 ) or limewater
7) Ammonium hydroxide (NH4OH) or ammonia water
8) Magnesium hydroxide ( Mg(OH)2 ) or milk of magnesia
Why do we care?
• The pH of fluids w/in most cells in the human
body must generally be kept btw 6.5 & 7.5.
(Is that acidic or basic?)
If the pH is higher or lower, it will affect
the chem rxns that take place in the cells.
• buffers – weak acids or bases that are used to
control the acidity or basicity of a
substance; they prevent sharp sudden
‘s in pH (remember:
= change)
PH LAB
Checkpoint
• What is more acidic?
– A solution with a pH of 6
– A solution with a pH of 2
– A solution with a pH of 14
• How do their concentrations of H+ ions
compare? Which has more?
• What about the OH- ions?
So what is a macromolecule?
• macromolecules (a.k.a. polymers)
- huge organic molecs composed of smaller
organic molecs
- made up of smaller molecs called monomers
- made via a process called polymerization
• there are 4 groups of organic cmpds found in living
things: (in no particular order)
#1 carbs
#2 lipids
#3 nucleic acids
#4 proteins
If I were you I would…
create a chart that includes the following
information:
- what the molec does = purpose
- what it’s made of = structure
- common name
- source
Carbohydrates
• purpose: - E source
- plants use it for structure
• made of: C, H, & O in a 1:2:1 ratio
*simple sugars (monosaccharides)
make up complex sugars
(polysaccharides)*
• common name:
• source:
Starch
Glucose
Carbohydrates
Lipids
• purpose: - store E
- parts of membranes
- waterproofing
• made of: glycerol & fatty acid
• common name:
• source:
LE 5-12a
Stearic acid
Saturated fat and fatty acid.
LE 5-12b
Oleic acid
cis double bond
causes bending
Unsaturated fat and fatty acid.
Lipids
Nucleic Acids
• purpose: store & transmit hereditary info
• consist of 3 parts:
• common name:
• source:
#1 - 5-C sugar
#2 - phosphate group
#3 - nitrogenous base
Proteins
• purpose : - regulate chem rxns (enzymes)
- form muscles & bones
- transport in & out of cell
- fight disease
• made of: - amino acids
- which have amino (NH2) &
carboxyl (COOH) gps
• source:
Proteins
Protein Structure
General Structure
Amino
Group
CarboxylG
roup
Alanine
Serine
Remember the blue & green sections?
Amino
acids
How You Should Eat Your Macromolecules
A Balanced Meal
Fiber and the American Diet
How to
Read a
Food
Label
How to
Read a
Food
Label
2. INGREDIENTS
• listed in descending
order of weight
• required on most
foods
• sources of some will
be stated by name to
help people better
identify ingredients
3. % of NUTRITION BASE
• is a footnote that is on
all labels
• the % of daily values
are based on a 2,000
calorie diet
• this is based on
current dietary
guidance
• facilitating the basics
of planning a good
diet
4. Key Nutrients (+)
• choose products with a higher
% of daily value from the key
nutrients
• nutrients with over 10% Daily
Value are considered good
sources
key important nutrients are:
•dietary fiber
•protein
•Vitamin A
•calcium
•vitamin C
•iron
Reasons the 6 Key Nutrients*
are Good for Your Health
•
•
•
•
•
•
protein (5g or more): body cell growth
dietary fiber: regulation of digestion
vitamin A: night vision
vitamin C: healing of tissue
iron: health blood
calcium: strong bones and teeth
nutrients* that relate to health concerns as heart disease, cancer, osteoporosis
5. Excessive Nutrients (-)
•over 200 calories is too many
•10 % or more of fat,
cholesterol, and sodium is
excessive
• too much can cause health
problems
• eat in moderation
Some of the nutrition slides from
this PowerPoint were created by
Linda Aldridge Ellision
Capital High School
2/4/2000
Types of Rxns
• anabolic = produces substance (creates pot E);
consumes E
ex: monomers put together to make polymers
• catabolic = breaks down a substance (creates
thermal E); E that was stored
becomes available for work
ex: like cellular respiration
• some chem rxns release E and they often occur
spontaneously = exergonic
ex: H2 + O2  H2O
(can you balance that?)
The E is released as heat!
• some chem rxns absorb E and won’t occur unless the E is
supplied = endergonic
ex: the reverse of the above rxn
H2O  H2 + O2
This rxn will not occur by itself, it requires that much E…
activation E – the E needed to get a
rxn started
Enzymes
• catalyst – a substance that speeds up the rate of a
chem rxn
• enzymes are biological catalysts; they speed up
chem rxns that take place in cells; they lower the
activation E
ex: the rxn used to remove CO2 from the body =
CO2 + H2O  H2CO3
If left by itself this rxn would take too long & CO2
would build up in the body so there is a specific
enzyme (carbonic anhydrase) available to do this
job specifically.
Activation E
Reaction pathway
without enzyme
Reactants
Reaction pathway
with enzyme
Activation energy
without enzyme
Activation
energy
with enzyme
Products
Can you decipher what these graphs are
showing?
Energy-Absorbing Reaction
Energy-Releasing Reaction
products
Activation E
Activation E
reactants
reactants
products
enzymes are very specific!
each one will catalyze only 1 chem rxn
Look at the video!
• http://www.youtube.com/watch?v=XTUm-75PL4&safe=active
What can affect enzymes?
• denaturation = to alter the original state
• changes in pH & temp: even slight changes
can denature an enzy = v. dangerous…
...Why?