1.1- Formulae and Equations

Question 1

(a) Formulae of some common substances

Water
Oxygen
Hydrogen
Nitrogen
Carbon dioxide
Sulfur Dioxide
Hydrochloric acid
Sulfuric acid
Nitric acid
Sodium hydroxide
Sodium carbonate
Ammonia

Answer 1

Water- H₂O
Oxygen- O₂
Hydrogen- H₂
Nitrogen- N₂
Carbon dioxide- CO₂
Sulfur Dioxide- SO₂
Hydrochloric acid- HCl
Sulfuric acid- H₂SO₄
Nitric acid- HNO₃
Sodium hydroxide- NaOH
Sodium carbonate- Na₂CO₃
Ammonia- NH3

Question 2

(a) Charges on some common ions

Ammonium
Hydroxide
Sulphate
Nitrate
Carbonate

Answer 2

Ammonium- NH4+
Hydroxide- OH-
Sulphate - SO42-
Nitrate- NO3-
Carbonate- CO32-

Question 3

Oxidation numbers

Answer 3

Rules:
The oxidaton state of atoms in elements is always 0.
In compounds, the sum of the oxidation state is always 0.
In ions the sum of the oxidation states is equal to the charge on the ion.

Question 3

(b)

Oxidation states

Answer 3

Rules:

Fluorine(F):
-1

Oxygen(O):
-2

Hydrogen(H):
+1 (except in H-)

Chlorine(Cl):
-1