When `K_(2)Cr_(2)O_(7)` is converted to `K_(2)CrO_(4)`, the change in the oxidation state of chromium is

Options

A. 0
B. 6
C. 4
D. 3

Answer

To determine the change in the oxidation state of chromium when \( K_2Cr_2O_7 \) is converted to \( K_2CrO_4 \), we can follow these steps:

### Step 1: Determine the oxidation state of chromium in \( K_2Cr_2O_7 \)

1. **Write the formula**: The formula for potassium dichromate is \( K_2Cr_2O_7 \).
2. **Assign known oxidation states**:
- The oxidation state of potassium (K) is +1.
- The oxidation state of oxygen (O) is -2.
3. **Set up the equation**: Let the oxidation state of chromium (Cr) be \( x \). The formula can be expressed as:
\[ 2(+1) + 2(x) + 7(-2) = 0 \]
4. **Solve for \( x \)**:
\[ 2 + 2x - 14 = 0 \]
\[ 2x - 12 = 0 \]
\[ 2x = 12 \]
\[ x = 6 \]
Therefore, the oxidation state of chromium in \( K_2Cr_2O_7 \) is +6.

### Step 2: Determine the oxidation state of chromium in \( K_2CrO_4 \)

1. **Write the formula**: The formula for potassium chromate is \( K_2CrO_4 \).
2. **Assign known oxidation states**:
- The oxidation state of potassium (K) is +1.
- The oxidation state of oxygen (O) is -2.
3. **Set up the equation**: Let the oxidation state of chromium (Cr) be \( y \). The formula can be expressed as:
\[ 2(+1) + y + 4(-2) = 0 \]
4. **Solve for \( y \)**:
\[ 2 + y - 8 = 0 \]
\[ y - 6 = 0 \]
\[ y = 6 \]
Therefore, the oxidation state of chromium in \( K_2CrO_4 \) is also +6.

### Step 3: Calculate the change in oxidation state

1. **Determine the change**: The oxidation state of chromium in both compounds is +6.
2. **Calculate the change**:
\[ \text{Change} = \text{Final oxidation state} - \text{Initial oxidation state} = 6 - 6 = 0 \]

### Conclusion

The change in the oxidation state of chromium when \( K_2Cr_2O_7 \) is converted to \( K_2CrO_4 \) is **0**.

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