Why does the colour of copper sulphate solution change when an iron nail is dipped in it ?
When an iron nail is placed in a copper sulphate solution, iron displaces copper from copper sulphate solution forming iron sulphate, which is green in colour.
$\underset{Iron}{\mathop{F{{e}_{(s)}}}}\,+\underset{\begin{smallmatrix}
Copper\text{ }sulphate \\
\left( Blue\text{ }colour \right)~
\end{smallmatrix}}{\mathop{CuS{{O}_{4\left( aq \right)}}}}\,\to \underset{\begin{smallmatrix}
Iron\text{ }sulphate \\
\left( Green\text{ }colour \right)
\end{smallmatrix}}{\mathop{FeS{{O}_{4\left( aq \right)}}}}\,+\underset{Copper}{\mathop{C{{u}_{(s)}}}}\,$
Therefore, the blue colour of copper sulphate solution fades and green colour appears.
Give an example of a double displacement reaction other than the one given in image.
Explain the ''Rancidity'' terms with one example.
What is a balanced chemical equation ? Why should chemical equations be balanced ?
Explain the "Reduction'' in terms of gain or loss of oxygen with two examples.
$Fe _{2} O _{3}+2 Al \rightarrow Al _{2} O _{3}+2 Fe$
The above reaction is an example of a