When same quantity of electricity is passed for half an hour, the amount of Cu and Cr deposited are respectively `0.375` g and `0.30` g. Ratio of electrochemical equivalent of Cu and Cr is

Options

A. `0.8`
B. `1.25`
C. `2.5`
D. `1.62`

Answer

To find the ratio of the electrochemical equivalents of copper (Cu) and chromium (Cr), we can use Faraday's laws of electrolysis. According to these laws, the weight of a substance deposited during electrolysis is directly proportional to its electrochemical equivalent.

### Step-by-Step Solution:

1. **Identify the Given Data:**
- Weight of copper deposited (W_Cu) = 0.375 g
- Weight of chromium deposited (W_Cr) = 0.30 g

2. **Write the Relationship:**
According to Faraday's laws, the relationship between the weights of the metals deposited and their electrochemical equivalents (E_Cu for copper and E_Cr for chromium) can be expressed as:
\[ \frac{W_{Cu}}{W_{Cr}} = \frac{E_{Cu}}{E_{Cr}} \]

3. **Substitute the Given Values:**
Substitute the values of W_Cu and W_Cr into the equation:
\[ \frac{0.375}{0.30} = \frac{E_{Cu}}{E_{Cr}} \]

4. **Calculate the Ratio:**
Now, calculate the left side of the equation:
\[ \frac{0.375}{0.30} = 1.25 \]
Therefore, we have:
\[ \frac{E_{Cu}}{E_{Cr}} = 1.25 \]

5. **Conclusion:**
The ratio of the electrochemical equivalents of copper to chromium is:
\[ E_{Cu} : E_{Cr} = 1.25 : 1 \]

### Final Answer:
The ratio of the electrochemical equivalent of Cu to Cr is 1.25:1.

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