Reactions of Acids

Acids can react with a variety of different chemicals.

These are normally NEUTRALISATION REACTIONS

We have looked at ACIDS + ALKALIS so far.

ALKALIS are part of a much larger group of chemicals which neutralise acids called BASES.

Reactions of Acids

There are 4 different types of BASES to investigate:

(1)Metal hydroxides (alkalis)

(2) Metal Oxides

(3) Metal Carbonates

(4) Metals

(1) Acids with Metal Hydroxides

Experiment:Investigating acids & alkalis

Acid + Alkali Salt + Water

Notes:• Metal Hydroxides (alkalis) are the soluble form of bases• H+ from the acid combine with the OH- from the alkali to make water• The salt forms from the NEGATIVE ION from the acid and the POSITIVE ION from the alkali• This reaction gives out heat (EXOTHERMIC)

(1) Acids with Metal Hydroxides

What is a SALT?• A salt is the product of a neutralisation reaction

• They are substances where the H+ ion of the acid has been replaced by a POSITIVE METAL ION (or Ammonium)

Starter Question

What is the NAME of the salt that would be formed fromthe reaction of:

(i) Hydrochloric acid and Calcium Hydroxide(ii) Sulphuric acid and Magnesium Hydroxide(iii) Nitric acid and Ammonium Hydroxide

(2) Acids with Metal Oxides

Experiment:Investigating acids & metal oxides

Acid + Metal Oxide Salt + Water

Notes:• All metal oxides react with acids• Again the salt is formed from the acid where the H+ ion has been replaced with the POSITIVE METAL ION from the metal oxide

(3) Acids with Metal Carbonate

Experiment:Investigating acids & metal carbonates

Acid + Metal Salt + Water Carbonate + Carbon Dioxide

Notes:• Metal Carbonates all contain the carbonate (CO3

2-) ion• CARBON DIOXIDE is given off• Carbon dioxide can be detected as it turns LIMEWATER CLOUDY

(4) Acids with Metals

Experiment:Investigating acids & metal carbonates

Acid + Metal Salt + Hydrogen

Notes:• The Group 1 & 2 metals will also react but is dangerous! • Hydrogen gas is produced• As with all other reactions, a SALT is formed

Summary of Acid Reactions

Acid + Metal Salt + Water Carbonate + Carbon Dioxide

Acid + Metal Oxide Salt + Water

Acid + Metal Salt + Hydrogen

Acid + Alkali Salt + Water

Acid Rain

Acid rain forms from twomain pollutant gasesdissolving in atmospheric water (rain).

The two gases are:• Sulphur Dioxide• Oxides of Nitrogen

(1) Sulphur Dioxide

Sulphur is found as an impurity in fossil fuels.

When it burns in oxygen it produces SULPHUR DIOXIDE.

This then dissolves in atmospheric water and falls as ACID RAIN.

(2) Oxides of Nitrogen (NO, NO2)

The spark plug in a car provides enough energy for nitrogen and oxygen to react.

This creates OXIDES of NITROGEN – these are normally shown as NOx (eg NO, NO2).

These oxides can dissolve in atmospheric water (clouds) and fall as ACID RAIN

N2O2

NO2NO

NO2

NO

NO

NO2