Chemical Reactions Year 12 Chemistry Students Must Know

Combustion of a Carbon Compound

Hydrocarbon + Oxygen → Carbon Dioxide Gas + Liquid Water

E.g. 2C₈H₁₈(l) + 25O₂(g) → 16CO₂(g) + 18H₂O(l)

Metals with Acids

Metal + Acid → Salt + Hydrogen gas

E.g. Zn(s) + 2HCl(aq) → ZnCl₂(aq) + H₂(g)

Carbonates with Acids

Carbonate + Acid → Salt + Carbon Dioxide Gas + Liquid Water

E.g. Na₂CO₃(aq) + 2HCl(aq) → 2NaCl(aq) + CO₂(g) + H₂O(l)

Oxidation

Metal → Metal Ion + Electron/s

E.g. Cu(s) → Cu²⁺(aq) + 2e^–

Trying to find the formula for higher Chemistry marks?

Reduction

Metal Ion + Electron/s → Metal

E.g. Ag⁺(aq) + e^– → Ag(s)

Redox (Reduction-Oxidation Reactions)

This reaction involves the transfer of electron/s from one reactant to another. This thus results in both a reduction and oxidation reaction occurring. To obtain the redox reaction, you can either write the net ionic equation for a displacement reaction (option 1) or add reduction and oxidation reactions together (option 2).

E.g. OPTION 1:

Cu(s) + 2AgNO₃(aq) → Cu(NO₃)₂(aq) + 2Ag(s)

Cu(s) + 2Ag⁺(aq) + 2NO₃^– → Cu²⁺(aq) + 2NO₃^– + 2Ag(s)

Cu(s) + 2Ag⁺(aq) + 2NO₃^– → Cu²⁺(aq) + 2NO₃^– + 2Ag(s)

Cu(s) + 2Ag⁺(aq) → Cu²⁺(aq) + 2Ag(s)

E.g. OPTION 2

NOTE: BOTH THE CONSERVATION OF MASS AND CHARGE MUST BE SHOWN IN YOUR EQUATION!

Cu(s) → Cu²⁺(aq) + 2e^–

                                    +

2Ag⁺(aq) + 2e^– → 2Ag(s)

__________________

Cu(s) + 2Ag⁺(aq) + 2e^– → Cu²⁺(aq) + 2e^– + 2Ag(s)

Cu(s) + 2Ag⁺(aq) → Cu²⁺(aq) + 2Ag(s)

Lime Water Test (Lime Water and Carbon Dioxide)

Calcium hydroxide + Gaseous carbon dioxide → Solid calcium carbonate + liquid water

I.e. Ca(OH)₂(aq) + CO₂(g) → CaCO₃(s) + H₂O(l)

Hydrogenation

Alkene + Hydrogen → Alkane

E.g. C₂H₄(g) + H₂(g) → C₂H₆(g)                                           Catalyst is Pt(s)

Bromination

Alkene + Bromine → Vicinal dibromide

E.g. C₂H₄(g) + Br₂(g) → CH₂BrCH₂Br(g)

Chlorination

Alkene + Chlorine → Vicinal dichloride

E.g. C₂H₄(g) + H₂(g) → CH₂ClCH₂Cl(g)

Hydrohalogenation

Alkene + HX → Alkyl halide

E.g. C₂H₄(g) + HBr(g) → CH₃CH₂Br(g)

Substitution with Bromine

Alkene + Bromine → Organobromine compound + Hydrogen bromide

E.g. C₂H₆(g) +Br₂(l) → C₂H₅Br(l) +HBr(g)           

NOTE: This reaction requires the presence of UV light.                                    

Hydration

Alkene + Water → Alkanol

E.g. C₂H₄(g) + H₂O(g) → CH₃CH₂OH(g)                             Catalyst is dilute H₂SO₄

Dehydration

Alkanol → Alkene + Water

E.g. CH₃CH₂OH(g) → C₂H₄(g) + H₂O(g)                             Catalyst is concentrate H₂SO₄

Fermentation of Glucose

Aqueous Glucose → Ethanol + Carbon Dioxide Gas

I.e. C₆H₁₂O₆(aq) → 2CH₃CH₂OH(aq) + 2CO₂(g)                  Catalyst is zymase (found in yeast)

Alpha Decay

Parent nucleus → Daughter nucleus + Alpha particle

E.g.  ²³⁸U → ²³⁴Th + ⁴He 

Beta Decay

Parent nucleus → Daughter nucleus + Beta particle

E.g. ¹⁴C → ¹⁴N + e^–

Neutralisation

Acid + Base → Salt + Liquid Water

E.g. HCl(aq) + NaOH(aq) → NaCl(aq) + H₂O(l)

Carbon Dioxide and Water

Aqueous carbon dioxide + Liquid water ↔ Carbonic Acid

I.e. CO₂(aq) + H₂O(l) ⇌ H₂CO₃(aq)

Formation of Sulfur Dioxide

Sulfur + Gaseous oxygen → Sulfur Dioxide

I.e. S(s) + O₂(g) → SO₂(g)

Formation of Sulfurous Acid

Gaseous sulfur dioxide + Liquid water → Sulfurous acid

I.e. SO₂(g) + H₂O(l) ⇌ H₂SO₃(aq)

Formation of Sulfur Trioxide

Gaseous sulfur dioxide + Gaseous oxygen → Sulfur trioxide

I.e. 2SO₂(g) + O₂(g) → 2SO₃(g)

Formation of Sulfuric Acid

Gaseous sulfuric acid + Liquid Water → Sulfuric acid

I.e. SO₃(g) + H₂O(l) → H₂SO₄(aq)

Formation of Nitrogen Monoxide

Gaseous oxygen + Gaseous nitrogen → Gaseous nitrogen monoxide

I.e. O₂(g) + N₂(g) → 2NO(g)

Formation of Nitrogen Dioxide

Gaseous nitrogen monoxide + Gaseous oxygen → Gaseous nitrogen dioxide

I.e. 2NO(g)  + O₂(g) → 2NO₂(g)

Formation of Nitric Acid

Gaseous nitrogen dioxide + Liquid water → Nitric acid + Gaseous nitrogen monoxide

I.e. 3NO₂(g) + H₂O(l) → 2HNO₃(aq) + NO(g)

Ionisation of an Acid in Water

Acid + Liquid Water → Hydronium Ion + Anion

E.g. HCl(aq) + H₂O(l) → H₃O⁺(aq) + Cl^‑(aq)

E.g. H₂SO₄(aq) + H₂O(l) → H₃O⁺(aq) + HSO₄^–(aq)

Esterification

Ethanoic acid reacts with ethanol in the presence of concentrated sulphuric acid as a catalyst to produce the ester, ethyl ethanoate. The reaction is slow and reversible. To reduce the chances of the reverse reaction happening, the ester is distilled off as soon as it is formed.

Alkanoic acid + Alcohol ⇌ Alkyl alkanoate + Water               (Catalyst: Concentrated sulfuric acid)

E.g. CH₃COOH(aq) + CH₃CH₂OH(aq) ⇌ CH₃COOCH₂CH₃(aq) + H₂O(l)

Formation of Ozone

1. Gaseous oxygen + High energy UV → Oxygen free radical

I.e. O₂(g) + UV → 2O^•(g)

2. Gaseous oxygen + Oxygen free radical → Gaseous ozone

I.e. O₂(g) + O^•(g) → O₃(g)

Destruction of Ozone

1. Photodissociation of CFC

E.g. CF₂Cl₂(g) + UV → CF₂Cl + Cl^•

2. Destruction of Ozone

I.e. O₃(g) + Cl^•(g) → ClO^•(g) + O₂(g)

3. Regeneration of Chlorine

I.e. ClO^•(g)+ O^•(g) → Cl^•(g) + O₂(g)