1. write down everything you can remember about: 2. do you remember any properties of an acid?
TRANSCRIPT
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?