Science 104- Monday October 6th

Schedule• Starter• Attendance•Return graded assignments•Lesson on pH•Memory Questions •Discussion on pH lab

Learning Intentions•To relate acids and bases to the pH scale •To understand that substances in nature have different pH values

Learning Curve

Classroom Routines

• Starters• Vocabulary Quizzes• Class website• Missing Class• Participation

StarterCopy down the following definitions Acid: A substance with a pH of less than 7. Vinegar and lemons are acidic substances with a sour taste. (page 467)Base: A substance with a pH of more than 7. Baking soda is an example of a base with a bitter taste. (page 467)pH: A scale that classifies substances according to their acidity and alkalinity. (page 190)

Word Association

When I say a word write down the first three words that come to mind.

READYSET

WORD: FIREREADY

SET WORD: ACIDS

Acids and Bases

• Acids and bases are two special kinds of chemicals

• Almost all liquids are either acids or bases to some degree.

• Whether a liquid is an acid or a base depends on the ions that are present

• When acids and bases mix they neutralize (cancel) each other

In Our Bodies

• Stomach releases hydrochloric acid to help breakdown food

• Heartburn is when the acid comes up the esophagus

• Stomach is protected by thick lining

• Food exiting the stomach is mixed with strong bases

In Nature

• Bee stings- Injects you with an acid- Causes pain and swelling

• Poison Ivy- Produce a basic substance- Severe irritation occurs

What should you do?

Page 188 Textbook

Apply a basic substance like baking soda

Apply an acidic substance like

vinegar or lemon

In Food

Acids - Sour Taste- Used for flavouring

Bases- Bitter Taste

In The Environment

Acid Rain- Damages buildings- Effects plants- Can change the

acidity of lakes http://www.ecokids.ca/PUB/eco_info/topics/frogs/acid_rain/play_acidlake.cfm

How do we know which is which?

One is an acid, one is a base and one is neutral.

Litmus Paper

Blue Litmus Paper

Red Litmus Paper

Acidic Substance

Turns Red Stays Red

Basic Substance

Stays Blue Turns Blue

Neutral Substance

Stays Blue Stays Red

Examples

• You dip a red litmus paper in a liquid and it stays red. What is your liquid (acid, base, neutral)

• What would you do next?

• What would you see?

pH Scale

pH Scale

How Does It Work

• Is a lemon (pH 2) only slightly more acidic than battery acid (pH 0.2)?

Does this makes?

Every increment is increase by a factor of 10!!

Universal Indicator

Battery Acid 0.2Stomach Acid 1.2Lemon Juice 2.0Vinegar 2.2Apple 3.0Tomato 4.2Rain 5.6Milk 6.6Pure Water 7Human Blood 7.4Baking Soda 8.2Milk of Magnesia 10.5Oven Cleaner 13.9

Homework

Memory Check Questions:Page 193

Questions #8-12