acids, bases and salts handout

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Practical Lesson Plan/ Test

Administrative Details

Date: 07/02/2011 11/02/2011

Subject: Chemistry

Grade: 11 Confidence

Number of students: 33

Duration: 35 minutes per session

Lesson Topic: Reactions of Acids and Base

Teaching Strategies:

i. Experimentation

ii. Discussion

General Objectives:

Students should:

1.

Specific Objectives

At the end of the lesson students will be able to:

1.1explain the reactions of acids with:

a. Metals

b. Metal Carbonates

c. Metal Hydrogen Carbonates

d. Bases

e. Metallic Oxides (Basic Oxides).

Previous knowledge:

Student must be able to:

Define the term metal

Identify the symbols of various elements

Instructional Materials:

i. chalkboard/whiteboard

ii. chalk/marker

iii. Laboratory apparatus and material


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iv. Handout

v. Text Book

Procedure

Introductory Activity-

The teacher will begin the lesson with a Do now activity here the students will watch music

video that summarizes the properties of acids and base as well as their reactions. The students are

required to make notes and use the tips to plan and design their experiment.

Developmental Activity-

Step 1

The students will work in their groups. Each group will be given a card with the reactions of acids

with Metals, Metal Carbonates and Metal Hydrogen Carbonates, Bases, Metallic Oxides

(Basic Oxides).

Step 2

Based on this, each group will plan and design a laboratory activity to confirm the information that

they are reviewing.

Step 3

Once this is done the students will be given the opportunity to carry out the experiments that they

have planned to confirm the theory. The expected reactions are as follows:

Reactions of acids

How do Acids React with Metals?

Let us do more activities to understand the chemical nature of acids and bases.

Action on Metals

Let us look at the way acids react with metals.

a) All metals above hydrogen in the metal reactivity series generally react with dilute acids to form

their respective salt and liberate hydrogen.

Metal + Acid Salt + Hydrogen


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b) Very active metals like potassium, sodium and calcium also react similarly, but tend to explode

when combining with acids.

c) Nitric acid (of various concentrations) usually exhibits oxidizing property, rather than acidic

properties. Metals such as magnesium combine with extremely dilute (1%) nitric acid to liberate

hydrogen.

How do Metal Carbonates and Metal Hydrogen Carbonates React with Acids?

Acids react with carbonates and hydrogen carbonates (bicarbonates) to form their respective salt,

water and carbon dioxide.

Carbonate/Bicarbonate + Acid Salt + Water + Carbon dioxide

How do Acids and Bases React with Each Other?


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Acids and bases are the chemical 'opposites' of each other and the action of an acid and a base

nullifies the effect of one on the other. This is known as a neutralization reaction.

Neutralization

In a neutralization reaction an acid combines with a base, neutralizing the power of acid with a

base and forms a molecule of water and the respective salt.

In general, a neutralization reaction can be written as:

Base + Acid Salt + Water

Examples:

Reaction of Metallic Oxides with Acids

Action with Basic Oxides

Oxides that can add on hydroxyl ions (OH-) to their molecules are called basic oxides. These

oxides get neutralized when they react with acids.

Basic oxide + Acid Salt + Water

Action with Basic Hydroxides

Acids undergo neutralization reaction with basic hydroxides to form salt and water.

Basic hydroxide + Acid Salt + Water


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Definition of terms

1. An acid is a substance which reacts with abase. Commonly, acids can be identified as

tasting sour, reacting with metals such as calcium, and bases like sodium carbonate.

Aqueous acids have pH of less than 7, and turn blue litmus paper red. Chemicals or

substances having the property of an acid are said to be acidic. An acid is a proton donor

2. Acid anhydride- An acid with one or more molecules of water removed; for example, SO3

is the acid anhydride of H2SO4, sulphuric acid. A chemical compound formed from

another, often an acid, by the removal of water.

3. Base- In chemistry is a substance that can accept hydrogen ions or more generally, donate

electron pairs. A soluble base is referred to as analkali if it contains and releases

hydroxide ions (OH) quantitatively.

4. Alkali is a base that is soluble in water.

5. Salt- Usually the term is applied to an ionic compound produced by reacting an acid with a

base. Salts are ionic compounds that can result from the neutralization reaction of

an acid and a base. Salts are ionic compounds composed

of cations (positively charged ions) and anions (negative ions) so that the product is

electrically neutral (without a net charge).

Examples: NaCl, KCl, CuSO4

6. Acidic - being or containing an acid; of a solution having an excess of hydrogen atoms

(having a pH of less than 7)
http://en.wikipedia.org/wiki/Base_(chemistry)http://en.wikipedia.org/wiki/Calciumhttp://en.wikipedia.org/wiki/Sodium_carbonatehttp://en.wikipedia.org/wiki/Chemistryhttp://en.wikipedia.org/wiki/Hydrogen_ionhttp://en.wikipedia.org/wiki/Alkalihttp://en.wikipedia.org/wiki/Alkalihttp://en.wikipedia.org/wiki/Ionshttp://en.wikipedia.org/wiki/Stoichiometryhttp://chemistry.about.com/library/glossary/bldef540.htmhttp://chemistry.about.com/od/chemistryglossary/g/compounddef.htmhttp://chemistry.about.com/od/acidsbases/a/aa110204a.htmhttp://chemistry.about.com/library/glossary/bldef100.htmhttp://chemistry.about.com/library/glossary/bldef5130.htmhttp://en.wikipedia.org/wiki/Base_(chemistry)http://en.wikipedia.org/wiki/Calciumhttp://en.wikipedia.org/wiki/Sodium_carbonatehttp://en.wikipedia.org/wiki/Chemistryhttp://en.wikipedia.org/wiki/Hydrogen_ionhttp://en.wikipedia.org/wiki/Alkalihttp://en.wikipedia.org/wiki/Ionshttp://en.wikipedia.org/wiki/Stoichiometryhttp://chemistry.about.com/library/glossary/bldef540.htmhttp://chemistry.about.com/od/chemistryglossary/g/compounddef.htmhttp://chemistry.about.com/od/acidsbases/a/aa110204a.htmhttp://chemistry.about.com/library/glossary/bldef100.htmhttp://chemistry.about.com/library/glossary/bldef5130.htm


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7. An amphoteric oramphiprotic substance is a compound that can react as an acid as well

as abase.[1] The word is derived from the Greek word amphoteroi ( ) meaning

"both". Many metals (such as zinc,tin, lead, aluminium, andberyllium) and most

metalloids have amphoteric oxides or hydroxides. Amphoteric substances can either donate

or accept aproton. Examples include amino acids andproteins, which have amine and

carboxylic acid groups, and self-ionizable compounds such as waterand ammonia.

8. Amphoteric oxide An amphoteric oxide is an oxide that can act both as an acid and as a

base. An example is aluminium oxide, Al2O3. It reacts with acids to form the

corresponding aluminium salt, and with bases to form salts called aluminates.

Example reactions

Al2O3 + 6HCl 2AlCl3 + 3H2O

Al2O3 + 2NaOH Na2Al2O4 + H2O

9. Neutral Oxides are non-metal oxides which do not react with acids or bases. All neutral

oxides are monoxides (e.g. Carbon monoxide)

Reaction of non - oxidizing acids (HCl) and hydrogen carbonates

Sodium Hydrogen Carbonate + Hydrochloric Acid --> Water + Carbon Dioxide + Sodium

Chloride

NaHCO3 + HCl --> H2O + CO2 + NaCl

Reactions of acids

How do Acids React with Metals?

Let us do more activities to understand the chemical nature of acids and bases.

Action on Metals

Let us look at the way acids react with metals.
http://en.wikipedia.org/wiki/Acidhttp://en.wikipedia.org/wiki/Base_(chemistry)http://en.wikipedia.org/wiki/Amphoterism#cite_note-0http://en.wikipedia.org/wiki/Zinchttp://en.wikipedia.org/wiki/Tinhttp://en.wikipedia.org/wiki/Leadhttp://en.wikipedia.org/wiki/Aluminiumhttp://en.wikipedia.org/wiki/Berylliumhttp://en.wikipedia.org/wiki/Metalloidshttp://en.wikipedia.org/wiki/Protonhttp://en.wikipedia.org/wiki/Amino_acidhttp://en.wikipedia.org/wiki/Proteinhttp://en.wikipedia.org/wiki/Aminehttp://en.wikipedia.org/wiki/Carboxylic_acidhttp://en.wikipedia.org/wiki/Molecular_autoionizationhttp://en.wikipedia.org/wiki/Waterhttp://en.wikipedia.org/wiki/Ammoniahttp://en.wikipedia.org/wiki/Acidhttp://en.wikipedia.org/wiki/Base_(chemistry)http://en.wikipedia.org/wiki/Amphoterism#cite_note-0http://en.wikipedia.org/wiki/Zinchttp://en.wikipedia.org/wiki/Tinhttp://en.wikipedia.org/wiki/Leadhttp://en.wikipedia.org/wiki/Aluminiumhttp://en.wikipedia.org/wiki/Berylliumhttp://en.wikipedia.org/wiki/Metalloidshttp://en.wikipedia.org/wiki/Protonhttp://en.wikipedia.org/wiki/Amino_acidhttp://en.wikipedia.org/wiki/Proteinhttp://en.wikipedia.org/wiki/Aminehttp://en.wikipedia.org/wiki/Carboxylic_acidhttp://en.wikipedia.org/wiki/Molecular_autoionizationhttp://en.wikipedia.org/wiki/Waterhttp://en.wikipedia.org/wiki/Ammonia


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a) All metals above hydrogen in the metal reactivity series generally react with dilute acids to form

their respective salt and liberate hydrogen.

Metal + Acid Salt + Hydrogen

b) Very active metals like potassium, sodium and calcium also react similarly, but tend to explode

when combining with acids.

c) Nitric acid (of various concentrations) usually exhibits oxidizing property, rather than acidic

properties. Metals such as magnesium combine with extremely dilute (1%) nitric acid to liberate

hydrogen.

How do Metal Carbonates and Metal Hydrogen Carbonates React with Acids?

Acids react with carbonates and hydrogen carbonates (bicarbonates) to form their respective salt,

water and carbon dioxide.

Carbonate/Bicarbonate + Acid Salt + Water + Carbon dioxide


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How do Acids and Bases React with Each Other?

Acids and bases are the chemical 'opposites' of each other and the action of an acid and a base

nullifies the effect of one on the other. This is known as a neutralization reaction.

Neutralization

In a neutralization reaction an acid combines with a base, neutralizing the power of acid with a

base and forms a molecule of water and the respective salt.

In general, a neutralization reaction can be written as:

Base + Acid Salt + Water

Examples:

Reaction of Metallic Oxides with Acids

Action with Basic Oxides

Oxides that can add on hydroxyl ions (OH-) to their molecules are called basic oxides. These

oxides get neutralized when they react with acids.

Basic oxide + Acid Salt + Water


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Appropriate method of salt preparation ( Sulphates, nitrates, chlorides, carbonates

Insoluble salts by Ionic precipitation

A salt is built from two kinds of ions. The salt as a whole is uncharged, which means

the charge of two ions "take each other out". If the positive ion (cation) has one

positive charge, and the negative ion (anion) has one negative charge, we need one

of the cation and one of the anion to construct an uncharged salt.

Precipitation

The ionic bond within a salt are of different strength depending on what ions the salt consists of. A

salt where the ions binds strongly together will not be dissolved in water. The reason to why some

ions bind stronger to each other are:


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The charge of the ions are equally big.

The difference in electronegativity between the ions is low.

The ions are equal in size.

If we mix two salt-solutions with each other (where both salts are completely dissolved in their

own solution), a new combination of ions may create an insoluble salt which precipitates (becomes

a solid while in water). This can be seen as a kind of fog in the mixed solution.

Which salt precipitates?

There are certain rules of thumb when identifying which salt could be the precipitation when two

salt solutions were mixed with each other:

All salts containing nitrate (NO3-) are soluble in water.

All salt containing alkali metals are soluble in water.

With the help of these two rules of thumb, one can estimate what salt is precipitated.

A solution ofBaCl2 is mixed with a solution ofAgNO3 and a precipitation is seen. The two salts

which in theory could produce the precipitation are the two new salts which can be created from

the ions in the solution. These are AgCl och Ba(NO3)2. With the help of the rules of thumb above,

we can assume that Ba(NO3)2 is soluble because it contains the nitrate ion. AgCl is therefore the

salt that precipitates.

Examples of common insoluble salts

AgCl as well as all other combinations of the silver ion with any halogen ion. BaSO4

Soluble salts by Direct combination and replacing hydrogen ions of an acid directly or on

directly

By a metal or ammonium radical

Distinguishing between acid salts and normal salts

Neutralization reactions using indicators and temperature change

acids, bases and salts handout

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