“Pollution” by Tom Lehrer

 

Time was when an American about to go abroad would be warned by his friends or the guidebooks not to drink the water,

but times have changed and now a foreigner coming to this country might be offered the following advice:

 

If you visit American city, You will find it very pretty

Just two things of which you must beware: Don't drink the water and don't breathe the air

 

Pollution, pollution, They got smog and sewage and mud

Turn on your tap And get hot and cold running crud

 

See the halibuts and the sturgeons being wiped out by detergents

Fish gotta swim and birds gotta fly, but they don't last long if they try

 

Pollution, pollution. You can use the latest toothpaste

And then rinse your mouth with industrial waste

 

Just go out for a breath of air and you'll be ready for Medicare

The city streets are really quite a thrill: If the hoods don't get you, the monoxide will.

 

Pollution, pollution. Wear a gas mask and a veil

Then you can breathe, long as you don't inhale.

 

Lots of things there that you can drink but stay away from the kitchen sink

The breakfast garbage that you throw in to the bay, they drink as lunch in San José.

 

So go to the city, see the crazy people there: Like lambs to the slaughter

They're drinking the water and breathing [cough] the air.

Solutions and Colloids

Solutions definition

Solutions

9 (actually 7 or 5) types of solutions

Solution is a dynamic equilibrium processas a balance of dissolving and precipitating

Why do substances dissolve?(potential solutes)

Thermodynamic parts of the dissolving process

Energy diagram for dissolving

Change in solubility with Temperature

for gaseous solutes for solid (ionic) solutes

Heat to “de-gas” solutions

A beaker of cold tap water develops air bubbles as it warms to room temperature.

Most ionic solutes increase in solubility as temperature increases

Effects of pressure of solubility of gases

A sample problem & applications of Henry’s Law

Some reasons to learn about

solubilities(Uses and

Applications of Solubility)

Miscible and ImmiscibleWater and alcohol are miscible.

Oil-and-water is an immiscible system.

Classification of solvents

As the organic alcohol part of the molecule is shortened, the solubility in water increases and the solubility of NaCl in the alcohol increases (see below).

Ionic solids dissolve in water because they become hydrated by water

Hydration of ions provides the energy of hydrationwhich is the main exothermic part of the energy of dissolving

Colloidal Dispersions

Suspension or

under microscope

beyondmicroscope

Eight types of Colloids (out of a possible 9)

with names

Properties of Colloids

Tyndall effect

Projector’s Light off Projector’s White light on

Light beam is invisible in a true solution, but the beam is seen when it passes through any colloidal dispersion because the light is scattered by the colloidal-sized “micro-droplets” (Rayleigh scattering).

Whenever you can see a beam of light (like the headlight beam of a car) it is due to the Tyndall effect through fog, mist, smoke or other colloid.

Laser beam visible in acolloidal dispersion.

Brownian motiondiscovered by botanist, Robert Brown, 1827

• http://groups.physics.umn.edu/demo/thermo/movies/4D1020.mov

• http://www.youtube.com/watch?v=4tt7M2fpI6U

To show Brownian motion, the ”micro-droplets” must be large enough that the microscope can see them, yet those “micro-droplets” must be small enough that they are visibly jostled or moved by the impacts of the surrounding unseen molecules. Brownian motion and Tyndall effect are characteristics of colloids.

Under a microscope, any colloidal sized “micro-droplets” are seen to move around in a random dance.

Colloidal silver: an alleged antibiotic

Salt-in-water solutionsof different concentrations

Dilute0.01 molar = 0.01 M = 0.01 moles/Liter

Not so dilute0.1 molar = 0.1 M

Concentrated0.6 molar = 0.6 M (seawater) = 3.5 % = 3.5 grams/Liter

Unsaturated, Saturated, and Supersaturated

Pictures taken seconds apartafter a seed crystal of Na2SO4 is dropped into a

supersaturated solution of Na2SO4

Supercooled glacial acetic acid

Four aspects of concentration units

Higher concentration does not always give a stronger effect

Part-per-Whole Ratio

Percentage calculations

Mole fraction

Definitions of the main concentration units used in chemistry

What to write, say, and think

Advantages and Disadvantages of each of the main concentration units

Some reasons to learn about concentration units(and their calculations)

Steps to prepare a solution

Preparation of a solution of known concentration

Problem on How to Prepare a Solution

Labeling a solution

Bottle labels usually do not list the full ionic composition

How to convert concentration units

Converting concentration units (continued)

Converting concentration units

Calculations for dilution of solutions

Before dilution After dilution

Calculations for mixing of solutions

Ten-fold serial dilution of potassium permanganate

Solution Stoichiometry

Titration stoichiometry

Here A is for acid, and B is for base.

Limiting Reactant using solutions

More solution stoichiometry

Q: If 37 mL of 0.52 M dichromate react with excess methanol, CH3OH,how many moles of formaldehyde will be formed if the dichromate is completely used up?

Highest & Lowest Possible Concentrations

Solution terminology

Solutions outline