03/09

Please, turn in your homework!

““The World We Create”The World We Create”NATS 101NATS 101Section 6Section 6

Although we may not have all of the evidence needed to claim that human actions are inducing

global warming in our planet, there is clear evidence that the pollutants we produce are

reshaping the face of our planet.

The World We Create

Carbon Dioxide (CO2) Nitrogen Oxides (NOx) Sulfur Oxides (SO2,SO3)

How?

Acidification: Human-Made

Pollutants that react with water alter they properties and can have a serious impact on

life in our planet.

A Water World

Water has a very important property:

It reacts with itself to produce two types of ion:

H2O + H2O H3O+ + OH-

H2OMade of It

Drink ItLeave in It

Water Properties

In pure water, for every 550,000,000 molecules of H2O, we have 1 H3O+ ion and 1 OH- ion:

Neutral WaterpH = 7

Measure of concentration of H3O+

ions.

There are many substances that react with water and

change the relative amount of H3O+ and OH- ions in

solution:

H3O+ OH-

ACIDS Increase DecreaseBASES Decrease Increase

Acids and BasesAcids are substances that can react with water to

produce more hydronium ions H3O+.

What acids do you know?

Acetic Acid

Ascorbic Acid

Carbonic Acid

Bases are substances that can react with water to produce more hydroxide ions OH-.

What bases do you know? Ammonia Sodium

Bicarbonate

pH Scale ACIDIC NEUTRAL BASIC

pH < 7 Acidic pH > 7 Basic

Small pH changes Life or Death

How can we

determine the pH of a solution?

How to Test for pH

• Litmus Paper

• Bromothymol Blue

• Phenolphthalein

• Boiled Red Cabbage

ACID-BASE INDICATORS

CLEAR LIQUIDS DEMONSTRATION

Class Experiment

• You will have 6 unknown liquids to test;

• Test each liquid for its pH, write down your results, and determine their identity.

You have 10 minutes

Substance Approximate pH

Muriatic Acid 1Lemon Juice 2

White Vinegar 3Lemon-Lime

Soda4

Seltzer Water 5Milk 6

Distilled water 7Baking Soda in

water 8

Antacids in water 9Bleach 10

Ammonia 11Lye 12

Discussion

What did you observe? Which of the substances were acidic?

Basic? What were the substances? What did you use besides pH to

determine this? Why would we need to know this?

ResultsTrial

#Unknown

liquid color code

Color with

indicator

Estimated PH

Acid or Base

Strong or Weak

Substance Hypothesis

1 C Pink 3 Strong acid

White Vinegar

2 E Fushia 5 Acid Seltzer 3 A Purple 7 Neutral Distilled

Water4 F Blue 8 Weak

BaseDissolved

Baking Soda

5 B Clear Yellow

10 Strong Base

Bleach

6 D Yellow 11 Strong Base

Ammonia

Investigating Pollutants

Pollutants such as CO2, NOx, SO2, and SO3

react with water and change its

pH.Let’s

investigate it!

Class Experiment Using your materials, determine the pH of a

carbon dioxide solution;

Record what you find;

Write three potential implications of these results for water and life in our planet.

You have 5 minutes

What happened?

When CO2 dissolves in water it forms carbonic acid:

CO2 + H2O H2CO3

H2CO3 + H2O H3O+ + HCO3-

What did you observe?

Is CO2 acidic, basic, or neutral?

Why is this significant?

What is the problem?

Ocean AcidificationThe average pH level of the ocean in the past

(1700s and earlier) has been ~8.179

In recent times the average pH of for the entire ocean has fallen to 8.104 (pH = -0.075)

~30% increased acidity.

Oceans have absorbed ~50% of all our emission.

The ENTIRE Ocean

Effects

The rate of CaCO3

production by coral

has decreased

6-11% since pre-industrial

times.

Higher T Higher Rate

Acid rain: rain with pH lower than 5.6.

Acid Rain

Primarily caused by sulphur dioxide (SO2) and nitrous oxides (NOx: NO, NO2, N2O)

Effects

The US: What do you see?

In 1995, Phase one of the Clean Air Act Amendments of 1990 took effect for 110 electrical utilities.

Most of these power plants were in the Eastern US.

Clean Air Act

NOx SO2

Larger impact

Project 2 available in D2L!

Due Tuesday March 23, 2:00 PM.

TWO MAJOR PREPARATION ACTIVITIES:TODAY:

Work in your groups addressing major misunderstandings.

THURSDAY:In class activities to reinforce ideas and help

you assess your understanding.“Begin work on one project question.”