Chemistry Review Unit 1C & D Investigating the Fish Kill and Cleaning Water.
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Transcript of Chemistry Review Unit 1C & D Investigating the Fish Kill and Cleaning Water.
Chemistry Review Unit 1C & D
Investigating the Fish Kill and Cleaning Water
Solutions
HomogeneousEqually 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?
To make a saturatedsolution of KCl at 50ºC, how much KCl would I add to 100 grams of water?
Problem Type II
But what if I don’t use 100 grams of water?Then use ratios.
46 g KCl_ = x g KCl100 g H2O 160 g H2O
(46)(160) = 100x
X =
How much KCl can dissolve in 160 g of water at 52oC?
Problem Type III
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
IMPORTANTAmount of solution = solute + solvent
solute + solvent
solute
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
PolarityPolar - two poles (+ and -) Ex. WaterWater Nonpolar - no charges or polesEx. OilOil
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 = neutralex. 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 - - Caused by Cl- + organic molecules
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