# presentation source

```Chemistry Review Unit 1C &amp;
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
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
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 47&ordm;C?
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
50&ordm;C, how much
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?
49&ordm;C
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
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:
 Mercury
•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
```