03/09 Please, turn in your homework! “The World We Create” NATS 101 Section 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 (CO 2 )  Nitrogen Oxides (NO x )  Sulfur Oxides (SO 2,SO 3 ) 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: H 2 O + H 2 O  H 3 O + + OH - H 2 O Made of It Drink It Leave in It

Water Properties In pure water, for every 550,000,000 molecules of H 2 O, we have 1 H 3 O + ion and 1 OH - ion: Neutral Water pH = 7 Measure of concentrati on of H 3 O + ions. There are many substances that react with water and change the relative amount of H 3 O + and OH - ions in solution: H3O+H3O+ OH - ACIDSIncreaseDecrease BASESDecreaseIncrease

Acids and Bases Acids are substances that can react with water to produce more hydronium ions H 3 O +. 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 SubstanceApproximate pH Muriatic Acid1 Lemon Juice2 White Vinegar3 Lemon-Lime Soda 4 Seltzer Water5 Milk6 Distilled water7 Baking Soda in water 8 Antacids in water 9 Bleach10 Ammonia11 Lye12

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?

Results Trial # Unknown liquid color code Color with indicator Estimated PH Acid or Base Strong or Weak Substance Hypothesis 1CPink3Strong acid White Vinegar 2EFushia5AcidSeltzer 3APurple7NeutralDistilled Water 4FBlue8Weak Base Dissolved Baking Soda 5BClear Yellow 10Strong Base Bleach 6DYellow11Strong Base Ammonia

Investigating Pollutants Pollutants such as CO 2, NO x, SO 2, and SO 3 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 CO 2 dissolves in water it forms carbonic acid: CO 2 + H 2 O  H 2 CO 3 H 2 CO 3 + H 2 O  H 3 O + + HCO 3 - What did you observe? Is CO 2 acidic, basic, or neutral? Why is this significant? What is the problem?

Ocean Acidification The 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 (  pH = ) ~30% increased acidity. Oceans have absorbed ~50% of all our emission.

The ENTIRE Ocean

Effects The rate of CaCO 3 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 (SO 2 ) and nitrous oxides (NO x : NO, NO 2, N 2 O)

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 NO x SO 2 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.”