KCET · Chemistry · Redox Reactions
The number of moles of electron required to reduce \( 0.2 \) mole of \( \mathrm{Cr}_{2} \mathrm{O}_{7}^{-2} \) to \( \mathrm{Cr}^{+3} \)
- A \( 12 \)
- B \( 0.6 \)
- C \( 1.2 \)
- D \( 06 \)
Answer & Solution
Correct Answer
(C) \( 1.2 \)
Step-by-step Solution
Detailed explanation
\[
\begin{array}{l}
\text { (C) } \\
\mathrm{Cr}_{2} \mathrm{O}_{7}{ }^{-2} \stackrel{6 e^{-}}{\rightarrow} 2 \stackrel{+3}{\mathrm{Cr}}
\end{array}
\]
\( 1 \) mol requires \( 6 \) mole of electrons
\( 0.2 \) mol requires \( \frac{0.2 \times 6}{1}=1.2 \mathrm{~mol} \) of electrons
\begin{array}{l}
\text { (C) } \\
\mathrm{Cr}_{2} \mathrm{O}_{7}{ }^{-2} \stackrel{6 e^{-}}{\rightarrow} 2 \stackrel{+3}{\mathrm{Cr}}
\end{array}
\]
\( 1 \) mol requires \( 6 \) mole of electrons
\( 0.2 \) mol requires \( \frac{0.2 \times 6}{1}=1.2 \mathrm{~mol} \) of electrons
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