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?

To make a saturated solution 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 KCl 100 g H 2 O 160 g H 2 O (46)(160) = 100x X = How much KCl can dissolve in 160 g of water at 52 o C? Problem Type III

Problem Type IV At which temperature will 80grams of KNO 3 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 IMPORTANT Amount 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 x = 200 ppm?? 20 = x 1001,000,000 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 -) Water Ex. Water Nonpolar - no charges or poles Oil Ex. Oil

Drawings of Dissolved Ionic Substances UnsaturatedSaturatedSupersaturated 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, H 2 SO 4 7 = neutral ex. NaCl, H 2 O 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 = Ca turns cloudy with Na 2 CO 3, less soap suds Ion Exchange Resin switches Ca 2+ 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