Chemistry Review Unit 1C &
D
Investigating the Fish Kill and
Cleaning Water
Solutions
 Homogeneous
 Equally distributed
 solute
-- what is dissolved (Ex. Salt)
 solvent - what dissolved (Ex. Water =
most common)
Three States of Solubility
Types of Solutions
 Unsaturated
 can’t
see
solute
 can add more
solute
 under the
curve
 Saturated
 can’t
see
solute
 “full”
 on
the curve
Types of Solutions
 Supersaturated
 can’t
see solute (but will
precipitate out when
cooled)
 needs to be heated
 “over full”
 above the curve
Reading Solubility
Curves
 Solute ALWAYS
goes on top of
fraction
 Water ALWAYS
goes on bottom of
fraction
 Graph ratio is
ALWAYS over 100
Problem Type I
What kind of a solution
do I have when 55g of
NaCl is dissolved in 100
ml of water at 47ºC?
Point falls above the
NaCl solubility curve!.
If only 33 grams of
salt was dissolved?
Problem Type II
To make a saturated
solution of KCl at
50ºC, how much
KCl would I add to
100 grams of water?
Problem Type III
But what if I don’t use
100 grams of water?
Then use ratios.
How much KCl can dissolve
in 160 g of water at 52oC?
46 g KCl_ = x g KCl
100 g H2O 160 g H2O
(46)(160) = 100x
X=
Problem Type IV
At which
temperature will
80grams of KNO3
dissolve in 100ml
of water and
make a saturated
solution?
49ºC
Gas Solubility Curves
• Solid - Solubility increases as temp. increases
• Gas -Solubility decreases as temp. increases
• Gas - Solubility increases as pressure increases
Solute Concentration
=
Amount of solute
Amount of solution
solute
solute + solvent
IMPORTANT
Amount of solution = solute + solvent
Concentration Problem
What is the percent concentration of salt if 38g of NaCl is
dissolved in 153ml of water?
Concentration Problem
•If I have a 20% solution of NaCl what is its
concentration in
•pph?
•20 (20/100)
•ppt?
20 = x
100 1000
x = 200
•ppm??
20 =
x
100 1,000,000
x = 200,000
How does water dissolve ionic
compounds?
 Positive side of water attracts negative
ion and surrounds it
 Water molecules “pull” until ion is free
and completely surrounded by water
 Same happens with negative side of
water and positive ion in compound
Polarity
Polar - two poles (+ and -)
Ex. Water
Nonpolar - no charges or poles
Ex. Oil
Drawings of Dissolved Ionic
Substances
Unsaturated
Saturated
Supersaturated
Oxygen (head) = -
pink = - ion
Hydrogen (ears) = +
yellow = + ion
Likes Dissolve Likes
“ POLAR WILL DISSOLVE IN OTHER POLAR”
“NONPOLAR WILL DISSOLVE IN OTHER
NONPOLAR”
“POLAR DOES NOT DISSOLVE IN
NONPOLAR AND VICE VERSA”
 Tells whether it is an acid, base, or
neutral
 1-6 = acid (more H+ ions)
 ex. HCl, H2SO4
 7 = neutral
 ex. NaCl, H2O
 8-14 = base (more OH- ions)
 ex. NaOH, Ba(OH)2
Heavy Metals
 Charged ions
so can
dissolve in
water
 Examples:
 Lead
 Mercury
 Cadmium
•Sources
•paint
•thermometers
•mines
•Damages
•brain
•proteins
•eyes
Water Cleaning
 Steps to cleaning
 pre-chlorination - kills bacteria
 flocculation - removes solid materials
 post-chlorination - keeps new bacteria from
growing
 aeration - improves taste
 Problems -
molecules
- Caused by Cl- + organic
Alternative Cleaning Methods
 Ozone/UV  pros = no extra chemicals in water, no
THM’s
 cons = bacteria can form later, costly
 Charcoal Filter
 pros = cleans the best, no THM’s
 cons = bacteria can form later, costly
 No pre-chlorination
 pros = less THM’s
 cons = not as clean
Water Softening
 Hard = Ca2+ -- turns
cloudy with Na2CO3,
less soap suds
 Ion Exchange Resin
 switches
Ca2+ for
2Na+
 Calgon
 forms
LARGE
molecule and binds up
Ca 2+
Fishkill
 Organic Carbon
 due to plants and algae
 more C, less oxygen
 Phosphates and Nitrates
 fertilizer
 more Phosphorous and Nitrates = more
plants
 Dissolved Oxygen
 needed in right amount for fish to survive
 more temperature, less oxygen