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