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The number of electrons donated from sub...

The number of electrons donated from substance(s) getting oxidized to the substance(s) getting reduced in the chemical equaton for the following reaction is:
`Cr_2O_(7)^(2-) + Fe^(2+) + C_2O_(4)^(2-)` `rarr` `Cr^(3+) +Fe^(3+) + CO_2`(Unbalanced)

A

6

B

5

C

3

D

4

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem of determining the number of electrons donated from the substance(s) getting oxidized to the substance(s) getting reduced in the reaction: \[ \text{Cr}_2\text{O}_7^{2-} + \text{Fe}^{2+} + \text{C}_2\text{O}_4^{2-} \rightarrow \text{Cr}^{3+} + \text{Fe}^{3+} + \text{CO}_2 \] we will follow these steps: ### Step 1: Identify Oxidation States 1. **Chromium in \(\text{Cr}_2\text{O}_7^{2-}\)**: - Let the oxidation state of Cr be \(x\). - The equation is: \(2x + 7(-2) = -2\). - This simplifies to \(2x - 14 = -2\), leading to \(2x = 12\) or \(x = +6\). - Thus, Cr is in the +6 oxidation state. 2. **Iron in \(\text{Fe}^{2+}\)**: - The oxidation state of Fe is +2. 3. **Carbon in \(\text{C}_2\text{O}_4^{2-}\)**: - Let the oxidation state of C be \(y\). - The equation is: \(2y + 4(-2) = -2\). - This simplifies to \(2y - 8 = -2\), leading to \(2y = 6\) or \(y = +3\). - Thus, C is in the +3 oxidation state. 4. **Products**: - In \(\text{Cr}^{3+}\), the oxidation state is +3. - In \(\text{Fe}^{3+}\), the oxidation state is +3. - In \(\text{CO}_2\), the oxidation state of C is +4. ### Step 2: Determine Changes in Oxidation States - **Chromium**: Changes from +6 to +3 (reduction, gains 3 electrons). - **Iron**: Changes from +2 to +3 (oxidation, loses 1 electron). - **Carbon**: Changes from +3 to +4 (oxidation, loses 1 electron). ### Step 3: Balance the Reaction - **Electrons Lost**: - For each \(\text{Fe}^{2+}\) oxidized to \(\text{Fe}^{3+}\), 1 electron is lost. - For each \(\text{C}_2\text{O}_4^{2-}\) oxidized to \(\text{CO}_2\), 2 electrons are lost (since there are 2 carbon atoms). - Total electrons lost from oxidation: - 1 electron from Fe + 2 electrons from C = 3 electrons lost. ### Step 4: Total Electrons Donated - The total number of electrons donated from the substances getting oxidized to the substances getting reduced is: - **Electrons gained by Cr**: 3 electrons (from +6 to +3). Thus, the number of electrons donated from the substances getting oxidized to the substances getting reduced in the reaction is **6 electrons**. ### Final Answer The number of electrons donated is **6**. ---
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