valency of Cu=2 and valency of S=2 but why chemical formula of copper sulphide = Cu2S

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Solution

1. Copper has variable valency.

2. It can exist in two ionic states:

Cuprous - Cu⁺
Cupric - Cu2+

3. In Cu₂S , it is the Cuprous form of copper having charge +1, thus it has chemical formula Cu₂S.

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Similar questions

Q. The chemical formula of sulphide of an element ‘X’ having valency 3 is

Why is CuSO₄the expected formula of Copper Sulphate and not Cu₂SO₄ when Copper has variable valency of Cu⁺ and Cu²⁺ ; Here the higher valency is used for the salt.

However in the case of Iron Sulphate the expected formula is FeSO₄ and not Fe₂(SO₄)₃ eventhough Iron also has variable valency of Fe²⁺ and Fe³⁺ ; Here the lesser valency is used for the salt.

Q. Skeleton equation of a chemical reaction is

C u_{2} S + C u S O_{4} \to C u + S O_{2}

Write its balanced chemical equation

Q. (a) What is the difference between a cation and an anion ? Explain with examples.
(b) The valencies (or charges) of some of the ions are given below :

Ion	Valency (Charge)	Ion	Valency (Charge)
Sodium ion	1+	Nitrate ion	1–
Copper ion	2+	Sulphide ion	2–

Using this information, write down the formulae of :
(i) Sodium sulphide
(ii) Copper nitrate

Q. When

C u_{2} S

is converted into

{C u}^{2 +}

and

{S O}_{2}

, then equivalent weight of

{C u}_{2} S

will be:

[M = molecular weight of

{C u}_{2} S

]

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valency of Cu=2 and valency of S=2 but why chemical formula of copper sulphide = Cu2S

1. Copper has variable valency. 2. It can exist in two ionic states: Cuprous - Cu+ Cupric - Cu2+ 3. In Cu2S , it is the Cuprous form of copper having charge +1, thus it has chemical formula Cu2S.

1. Copper has variable valency.

2. It can exist in two ionic states:

Cuprous - Cu⁺
Cupric - Cu2+

3. In Cu₂S , it is the Cuprous form of copper having charge +1, thus it has chemical formula Cu₂S.