Question

What is the salt formed when Copper (II) combined with sulphur (S) and how do you write the formula?

Answer 1

Hint:To answer this question we should talk about electro neutrality. According to electro neutrality an amount of charge can be balanced by an equal amount of opposite charge. So, we will determine the ion formed by sulphur according to the charge of copper ions. Then will determine the formula by balancing the opposite charges.

Complete step-by-step answer:Atoms form ions and react to give a molecule.It is given that the copper is present as ${\text{C}}{{\text{u}}^{{\text{2 + }}}}$. To form a neutral compound of copper and sulphur, we require $ - 2$ charge on sulphur.
${\text{S}}\, + \,{\text{2}}{{\text{e}}^ - } \to {{\text{S}}^{{\text{2}} - }}$
The copper (II) is known as copper ion and ${{\text{S}}^{{\text{2}} - }}$ ion is known as sulphide ion. So, be the reaction of copper and sulphide, the copper sulphide will form.Now, copper (II) ion ${\text{C}}{{\text{u}}^{{\text{2 + }}}}$ and sulphide ${{\text{S}}^{{\text{2}} - }}$ combine to form copper sulphide.
${\text{C}}{{\text{u}}^{{\text{2 + }}}}\, + \,{{\text{S}}^{2 - }} \to \,{\text{CuS}}$
So, the formula of copper sulphide is ${\text{CuS}}$.

Therefore, the salt formed when Copper (II) combined with sulphur (S) is copper sulphide and the formula of copper sulphide is CuS.

Note:When an atom donates electrons some other atom takes electrons. The number of electrons transferred by a cation depends upon the number of electrons that will be taken by an anion. Suppose if the copper ions donate two electrons to form copper (II) ions ,so sulphur will take two electrons so form sulphide ions. Sulphur is the member of the oxygen family, so it can show $ - 2$ oxidation state. We will combine the copper and sulphide ions in $1:1$ which gives the formula CuS and is neutral according to electro neutrality.