Lesson: Chemicals and Indicators

To make you think… https://www.youtube.com/watch?v=VrzbRZn5Ed4 Prince Ea Condense Earth’s timeline to 24 hours. Humans have been here for 3 seconds.

I need your full attention and EFFORT 9C: Start on slide 6 – as we did 1-5 already in lesson 9B: Start at the beginning ** Reminder that you are down to your last 4 classes of Enviro Chem unit. Unit exam is on June 1st. We start PAT review after that.

Lesson Chemical and Indicators (Write down what is in RED in booklet) World population is now over 7 billion. We all produce waste. 2 types: Persistent- eventually biodegrades (breaks down) ex) sewage Non- persistent- remains in environment for a very long time. Ex) DDT, mercury

Algal blooms (draw under chemicals and indicators) Chemicals from run-off getting into water sources. 1) Fertilizers get into lake (N,P,K) 2) Plants and algae BLOOM Fields Run off 3) Increase bacteria to break down organic matter N P K lake 4) Bacteria use O2 5) No O2 = dead lake

Biological Indicators AKA bioindicators Tells you about the health of the ecosystem Frogs are sensitive to changes in pH, temp, and toxicity. More likely to be born with birth defects.

What is the quality of oxygen in each lake? (Hint: Organisms that are representative of poor water quality may be found in any type of water, whereas organisms representative of good water quality are found only in water of good quality!!)   LAKE A: _____________ LAKE B: _____________ LAKE C: _____________ Good Poor Look at the 3 lakes up top. Use the key (to the right) to figure out what kind of water quality each lake is. Moderate

Chemical Indicators pH stands for “power of hydrogen”. More H+ ions (remember from chemistry when it gains of loses e-) Tells you acidity or alkalinity (aka base) Neutral ACID BASE 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

ON YOUR OWN Use a chromebook to find something that has a pH of each of these, and label in your booklet. Ex) hydrochloric acid has a pH of 0.

pH Tests ACIDS: pH 0-6.9 Taste sour (tart) Lots of hydrogen ions Because you cannot EAT things in a lab. We use indicators of pH. (fill these out on the pH chart) ACIDS: pH 0-6.9 Taste sour (tart) Lots of hydrogen ions Corrosive to metals

Neutral: pH 7 ex) water equal number of hydrogen to hydroxide ions

BASE (alkaline) pH 7.1- 14 Tastes bitter Slippery feeling (soap) Lots of hydroxide ions (OH-)

Write this under the “common characteristics” chart Other types of indicators: 1) Universal indicators: wide range of colours the turn. Ex) red cabbage (like the lab we did) 2) Phenolphthalein  is colourless in acid. Will turn pink in base (tests for base only) 3) Bromothymol Blue Is blue in a base. Turns yellow in acid (tests for acid only)

… continued ** Litmus paper  lichen that is used to test pH Blue litmus (remember BRA): Blue litmus turns Red in an Acid. Red litmus (RBB): Red litmus turns Blue in a Base

(next page) Acid Precipitation- a global concern Biggest issue is that acid rain does not stop at borders. Countries committed to cutting down on their harmful emissions still feel the effects of those who refuse to cut down.   Acid rain: Kills aquatic animals, destroys crops, breaks down structures. These oxides mix with moisture and water in the air and can form different compounds and eventually come down in the rain, snow, and sleet  They cause hydrogen (H) from water to form ions (H+), which makes it ACIDIC.   - When organic matter- like oil, gas, and coal- is burned it releases OXIDES (chemicals with oxygen) Ex.) Carbon Dioxide (Co2) Sulphur Dioxide (So2) Sulphur Trioxide (SO3) Nitrogen Dioxide (nO2)

https://www.youtube.com/watch?v=v09KnqiYi-c Simpson’s teach about acid rain

Using Chemistry to Control Acid Effects In order to get rid of a STRONG ACID, we can cancel its strength with a BASE and vice versa  called neutralization – creates water and a salt

Acidic lakes will be “limed” with a basic spray of calcium carbonate (limestone). Antacids neutralize stomach acid.

Homework Questions #3 (Should really be labeled as 4. (oops!) Your last set in this booklet. Complete for next science class.