1. Write down everything you can remember about:

2. Do you remember any properties of an acid?

Lesson 4

Learning Objectives:

•Describe the test for hydrogen (H) ions using acid/base indicators•Describe and explain the typical reactions of acids, using balanced formulae equations

A quick look at acids …

What do all acids have in

common?H

SO4

H

NO3

Cl

H

H ALL acids contain HYDROGEN – this

is important!

NameName FormulaFormula

Hydrochloric acid

Ethanoic Acid

Nitric Acid

Sulfuric Acid

HCl

CH3COOH

HNO3

H2SO4

INDICATORS are DYES that CHANGE COLOUR depending upon whether they are in ACIDIC or ALKALINE CONDITIONS.

Litmus

Red in acid

Blue in alkali

Methyl orange

Red in acid

Yellow in alkali

Universal indicator has a range of colours and a pH number to go with

the colours

1. Add 2cm depth of the acid to a test tube.2. Add a small amount of the three metals –

magnesium ribbon (1–2 cm), zinc granules and copper turnings (half a spatula) – each to a separate test tube of the acid.

3. If a gas is produced test it with a lighted splint.

1. Add half a spatula of sodium carbonate to a separate test tube of the acid, and observe what happens.

2. If a gas is produced, test it by bubbling it through limewater.

Metal + metal carbonates

Metal + Acid

K + HCl KCl + H2

K2 + H2SO4 K2SO4 + H2

K + HNO4 KNO4 + H2

Ca + HCl CaCl + H2

Ca2 + H2SO4 Ca2SO4 + H2

Ca + HNO4 CaNO4 + H2

…and so on!

H

SO4

H

Mg

H Cl

H Cl

Mg

?

H

SO4

H

Na ?

Any metal! It could be a +1 or +2 cation (positive ion) eg Na+ or Cu2+

This is a CO32- ion

H

SO4 Cu CO

OO

H

H

SO4 Na CO

OO

H

Na

?

H Cl CO

OO

H Cl

Na

Na

?

H Cl CO

OO

H Cl

Cu

?

SALTS SALTS

• When an acid reacts with a metal or a metal compound they make A SALT.

• Salts are a specific group of chemicals– they are all NEUTRAL (not acidic or

alkaline)

– they are made up of a metal part and the NON-HYDROGEN part of an acid.

sulphates

chlorides

nitrates

If you use these acids…

H

SO4

H

NO3

Cl

H

H

H2SO4

HCl

HNO3

• What type of salts do you think the following would form?–carbonic acid–stearic acid–phosphoric acid

Practice1. Nitric acid + potassium 2. Magnesium + hydrochloric acid 3. Iron carbonate + sulphuric acid 4. Zinc carbonate + hydrochloric acid 5. Zinc + sulphuric acid 6. Nitric acid + magnesium 7. Aluminium + hydrochloric acid 8. Potassium carbonate + nitric acid

Writing a general equation.

Metal + Acid Salt + hydrogen

Metal Carbonate + Acid carbon dioxide + salt + water

Predictions …

What do you think might be formed in the following?

hydrochloric acid and sodium hydroxide?

potassium hydroxide and sulphuric acid?magnesium oxide and hydrochloric acid?