The equivalent weight of $\mathrm{Cu}$ in ${\mathrm{Cu}}_2\mathrm{O}$ is?

Step 1: Equivalent mass:

• “Equivalent mass is equal to the molecular/atomic mass divided by the number of electrons involved in the reaction per molecule/atom/ion.”

Step 2: Formula for equivalent mass:

$\mathrm{Equivalent}\mathrm{mass}\mathrm{of}\mathrm{Element}=\frac{\mathrm{Atomic}\mathrm{mass}\mathrm{of}\mathrm{Element}}{\mathrm{Valency}}$

Step 3: Calculation for the equivalent mass of $\mathrm{Cu}$:

• The atomic mass of Copper$\left(\mathrm{Cu}\right)$ is $63.5\mathrm{g}$.
• The valency of Copper in Copper(I) oxide ${\mathrm{Cu}}_2\mathrm{O}$ is $+1$.

$$\begin{gathered} \mathrm{Equivalent}\mathrm{mass}\mathrm{of}\mathrm{Cu}=\frac{\mathrm{Atomic}\mathrm{mass}\mathrm{of}\mathrm{Cu}}{\mathrm{Valency}} \\ \mathrm{Equivalent}\mathrm{mass}\mathrm{of}\mathrm{Cu}=\frac{63.5\mathrm{g}}{1}=63.5\mathrm{g}{\mathrm{eq}}^{-1} \end{gathered}$$

Thus, the equivalent mass of $\mathrm{Cu}$ in ${\mathrm{Cu}}_2\mathrm{O}$ is $63.5\mathrm{g}{\mathrm{eq}}^{-1}$.