Question

An element M forms the oxide M2O3. What will be the formula of its sulphate?​

Answer 1

given

element M has a valency of 3.

When writing the formula of its sulphate, we need to know the valency of the sulphate ion which is a radical. From or previous knowledge, we know that the valence of a sulphate ion,SO₄²⁻ is 2. Therefore the sulphate of M can be written as:

M₂[SO₄]₃

Answer 2

An element M forms the oxide $M_{2}O_{3}$ . The formula of its sulphate is $M_{2}[SO_{4}]_{3}$.

• The given formula is $M_{2}O_{3}$ which clearly denotes that oxygen is a divalent with a valency of -2.
• It means the number of oxygen atoms present = 3.
• Also, the element M in the given formula is trivalent with a valency of 3.
• It means that the number of M atoms present = 2.
• Now, to form a formula of sulphate, it valency need to be determined and here the sulphate ion is a radical.
• In general, the sulphate ion $SO_{4}^{2-}$ has a valency of 2.
• So, the formula can be written as $M_{2}[SO_{4}] _{3}$.

Hence, the formula of its sulphate can be written as $M_{2}[SO_{4}] _{3}$.