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Solutions and pH
Solutions
Mixtures – a combination of substances
that retain their original properties
Ex. trail mix, air, salt water
Solutions
Solution – mixture of one or more substances
uniformly distributed in another substance.
Can be solid, liquid, gas
ex. Plasma (liquid)
brass (solid) copper and zinc
soda (liquid/gas) water and CO2
Solutions
2 parts:
1. Solute – substance being dissolved
2. Solvent- substance doing dissolving
Salt water:
salt = solute
water = solvent
Aqueous solutions- water is the solvent due to
hydrogen bonding
Water = universal solvent because it can dissolve
most things
Concentration
Concentration- amount of solute
dissolved in a fixed amount of solution
When no more solute can be
dissolved….solution is SATURATED
Salt will no longer dissolve

Acids & Bases
The Homeostasis of living things depends
on the degree of acidity (acid) and
alkalinity (base) in certain areas
Water
 Acids and bases are solutions made by the dissociation of
water
 Water naturally breaks down into ions of opposite charges,
this is called dissociation.
 Water will form these ions naturally (H3O+ & OH-) and in
EQUAL amounts.
H2O  H+ + OHThis is why water is NEUTRAL!
Hydronium (H3O+) ions = hydroxide (OH- ) ions
Acids & Bases
Acidity= measure of the amount of
hydronium (H3O+) ions dissolved
in a solution.
Alkalinity (AKA basic solution)= measure of
the amount of hydroxide (OH- ) ions
dissolves in a solution
Acids
- more H+ ions released
- pH < 7
- Sour taste
- Corrosive on metals
- Burns skin
• Ex. Orange juice,
• vinegar, sulfuric acid
*Homeostasis relevance- your
stomach must have a certain acidity
to function properly
Bases
-more OH- ions released
-
pH > 7
Tastes bitter
Slippery
Irritate the skin
- Ex. NaOH
- Homeostasis relevance- your
small intestine needs a certain
alkalinity (basic) to function
properly
pH Scale
- Used to measure the
amounts of H3O+ and OHions in a solution
- Tells you how acidic or
basic something is
- Ranges 0-14, 7 = neutral
above 7 = base
below 7 = acid
- Ten fold system
- Measure pH with litmus
paper
Buffers
Buffers- chemical substances that neutralize
small amounts of acids and bases
Ex. Acids { stomach acid & urine
Ex. Bases { blood & intestinal fluid
- If not at the proper pH level, these body systems
will not function properly and…
you’ll need to use a Buffer ex. Alka
seltzer