TOPIC:

ACIDS & BASES

Increase of science knowledge in students by adopting 21st century student centered teaching approach.

SHORT TERM GOALS

SHORT TERM GOALS:

OBJECTIVES

Elicit from children acids and bases that they encounter on a regular basis.

Bring in examples of common acids and bases. For example, baking soda is an easy base to bring in.

Oranges with their citric acid, or vinegar are easy acids to bring in.

Demonstrate what happens when you mix baking soda (a base) and vinegar (an acid), together.

Ask students why they think the reaction bubbles so much.

o Introduce the pH scale to students.

Explain that when scientists want to determine how

acidic or basic something is they use a scale of 0 to 14.

o Draw a diagram on the board.

o Show that the pH scale really just tells us about the

kind of ions a solution releases when it breaks down.

o Acidic solutions possess lots of hydrogen ions and

basic solutions possess lots of hydroxide ions.

o Tell children that acidic substances have a pH below 7.

o Explain that the lower the number is, the more acidic it is.

o Ask students what numbers they think very basic substances

have on the pH scale. Verify the bases have a pH above

seven and that the higher the number, the more basic it is.

o Ask students what they think a very neutral number will have

on the pH scale. They should guess the number seven. Ask

them which substances they think have a pH of seven. Let

them guess and then tell them the answer is distilled water.

INSTRUCTIONAL STRATEGIES:

Topic 21st century approaches

Modes/ Techniques

Acids & basesListening, speaking,

observing and

monitoring,

intervening,

encouraging.

Quiz, videos, web links.

SOLUTIONS TO ANTICIPATED CHALLENGESchallenges solutions

The principal may not agree with my new approach

I will share the course manual and my notes with my principal.

Parents may not understand my method

I will use my new word processing skills to create a presentation on acids and bases to inform parents of my new methods.

I do not own a computer I will stay after school to use a computer in the computer lab to create productivity tools.

There may be some students who do not want to work together.

I will randomly group students to encourage collaboration.

BLOOM’S TAXONOMY:

ACIDS AND BASES PRESENTATION SAMPLE:

Synopsis

Introduction

Definitions

Properties

Uses of acids and bases

Neutralization reaction

Introduction:

Acids and Bases Are All Around:

Have you ever used baking soda in the kitchen?

Maybe you have eaten salad dressing with vinegar in it – vinegar is a weak form of acetic acid.

Citrus fruits that you eat contain citric acid.

You also have acids and bases in your body. Human stomach contain hydrochloric acid that is used to digest food. The stomach acid must be kept away from the rest of the body because it is very harsh and can cause damage.

The lining of your stomach is specially built to survive the acidic environment.

The pH scale goes from 0 to 14.

Acids have pH numbers below 7.

The lower the number is, the stronger the acid. Very

strong acids include things like battery acid.

Bases have pH values above 7. The higher the number is,

the stronger the base.

An example of a very strong base is drain or oven cleaner.

Distilled water is a substance with a pH of 7 which is

neutral.

hat is pH?

DEFINITION OF ACIDS

Any of a class of substances whose aqueous solutions are

characterized by a sour taste, the ability to turn blue litmus red,

and the ability to react with bases and certain metals to form

salts.

A substance that yields hydrogen ions when dissolved in water.

A substance that can act as a proton donor.

.A substance that can accept a pair of electrons to form a

covalent bond.

A substance having a sour taste.

Two common definitions for acids

The Arrhenius definition

The Bronsted-Lowry definition.

The Arrhenius definition: “states that acids are substances which

increase the concentration of hydronium ions (H3O+) in solution”.

HCl --------------- H+ + Cl-

The Bronsted-Lowry definition : “states that an acid is a substance which can

act as a proton donor. Most acids encountered in everyday life are aqueous solutions, or can be dissolved in water, By the Bronsted-Lowry definition, any compound which can easily be deprotonated can be considered an acid”.

NaOH ------------ Na+ + OH-

COMMON EXAMPLES OF ACIDS:

Hydrochloric acid

Sulfuric acid

Nitric acid

Malic acid

Citric acid

Acetic acid

PROPERTIES OF ACIDS

Produce H+ Taste sour

React with bases to form salts and water

Corrode metals

DEFINITION OF BASES: About.com chemistry:

A base is a chemical species that donates

electrons or hydroxide ions or that accepts protons.

A soluble base is referred to as an alkali if it

contains and releases hydroxide ions (OH−).

Examples : are sodium hydroxide and ammonia.

Metal oxides, hydroxides are basic.

The Arrhenius definition: “states that bases are substances which

increase the concentration of hydroxide ions (OH- ) in solution”.

NaOH --------------- Na+ + OH-

The Bronsted-Lowry definition : “states that bases are substances that are

capable of splitting off or taking up hydrogen ions”.

NaOH ------------ Na+ + OH-

COMMON EXAMPLES OF BASES:

Sodium hydroxide

Calcium hydroxide

Magnesium hydroxide

Baking soda

PROPERTIES OF BASES

Produce OH- ions Taste bitter

soapy, slippery React with acids to form salts and water

Electrolytes

USES OF ACIDS:

Sulphuric acid is used in the battery of an

automobile

in the manufacture of fertilizers, rayon and

detergents.

Nitric acid is used to make fertilizers, explosives

and dyes.

NEUTRALIZATION REACTION:

Definition:

Neutralization reaction refers to acid and base reaction

producing salt and water.

The equivalent amounts of acid react with base to form

equivalent amounts of salt and water.

When the reaction is complete, acid and base are said to

neutralize each other. Since water is produced, neutralization

reaction is also referred as “water forming reaction”.

Acid + base salt + water

Consider reaction like :

NaOH + HCl NaCl + H2O

We can rewrite the reaction in ionic form as

Na+ + OH− + H+ + Cl− Na+ + Cl− +H2O

ACTIVITIES.

Acids and Bases Are All Around Questions

1. True or False. Acids and bases are common in everyday places

such as the kitchen.

2. Give an example of an acid found in something you can eat.

3. True or False. Acids and bases react with each other when they are

put together. (Think of the vinegar and baking soda).

4. What is the environment like inside of your stomach?

a. acidic

b. basic

5. The pH scale goes from _______ to ________.

6. Acids have pH numbers __________ than 7. a. greater than b. less than

7. Bases have pH numbers __________ than 7. a. greater than b. less than

8. A substance with a pH of 7 like distilled water is called _______.

9. Acidic solutions have lots of ______________ ions present.

10. A pH ___________ is something that can be used to determine the pH of a solution. a. chart b. indicator c. acid d. base

EXPERIMENTS:

A CHEMICAL REACTION:

This first experiment serves to introduce the concept of chemical

reaction and can be performed in an elementary school also.

It is useful to help children understand how acid substances react

with basic ones.

In half a glass of water, put a few teaspoons of baking soda and mix

in order to obtain a quite concentrated solution.

In the same glass, pour a spoon of vinegar.

As you can see, there will be an abundant production of foam .

A chemical reaction occurred between the baking soda (a basic

substance) and vinegar (an acid substance).

These two substances reacted with each other, producing a salt,

water, and carbon dioxide.

That is the gas which produced the little bubbles you observed.

In general, acid and basic substances react with each other,

producing a salt and often other substances like water and carbon

dioxide.

The salt produced by this reaction is sodium acetate:

If you want make the reaction more lively, use warm (not hot) water.

CH3COOH + NaHCO3 →CH3COONa + H2O + CO2

CH3COOH NaHCO3 CH3COONa H2O CO2

Acetic acid Baking soda Sodium acetate Water Carbon dioxide

RESOURCES:

Text books

Word processing, multimedia and spreadsheet

applications.

Intel ® teach program getting started course

manual.

CONCLUSION:

By implementing my newly acquired 21st century

teaching approaches students will be empowered

and will appreciate and gain a better knowledge of

General science.