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How many total moles of electrons are tr...

How many total moles of electrons are transferred when 1 mole of `Cr_(2)O_(7)^(2-)` oxidized `Fe^(2+)` to `Fe^(3+)` in acidic medium?

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To determine how many total moles of electrons are transferred when 1 mole of \( \text{Cr}_2\text{O}_7^{2-} \) oxidizes \( \text{Fe}^{2+} \) to \( \text{Fe}^{3+} \) in acidic medium, we can follow these steps: ### Step 1: Identify the oxidation states - The oxidation state of chromium in \( \text{Cr}_2\text{O}_7^{2-} \) can be calculated as follows: \[ 2x + 7(-2) = -2 \implies 2x - 14 = -2 \implies 2x = 12 \implies x = +6 \] So, the oxidation state of chromium in \( \text{Cr}_2\text{O}_7^{2-} \) is +6. - The oxidation state of iron in \( \text{Fe}^{2+} \) is +2, and in \( \text{Fe}^{3+} \) it is +3. ### Step 2: Determine the change in oxidation states - Chromium changes from +6 in \( \text{Cr}_2\text{O}_7^{2-} \) to +3 in \( \text{Cr}^{3+} \). The change in oxidation state is: \[ +6 \text{ to } +3 \implies 3 \text{ electrons are gained per chromium atom.} \] - For iron, the change is from +2 to +3, which means: \[ +2 \text{ to } +3 \implies 1 \text{ electron is lost per iron atom.} \] ### Step 3: Balance the reaction - Since there are 2 chromium atoms in \( \text{Cr}_2\text{O}_7^{2-} \), the total number of electrons gained by chromium is: \[ 2 \text{ Cr} \times 3 \text{ electrons} = 6 \text{ electrons.} \] - To balance the number of electrons lost by iron, we need 6 moles of \( \text{Fe}^{2+} \) to provide the 6 electrons needed for the reduction of \( \text{Cr}_2\text{O}_7^{2-} \): \[ 6 \text{ Fe}^{2+} \rightarrow 6 \text{ Fe}^{3+} + 6 \text{ electrons.} \] ### Step 4: Write the balanced half-reaction - The overall balanced half-reaction in acidic medium can be written as: \[ \text{Cr}_2\text{O}_7^{2-} + 6 \text{Fe}^{2+} + 14 \text{H}^+ \rightarrow 2 \text{Cr}^{3+} + 6 \text{Fe}^{3+} + 7 \text{H}_2\text{O} \] ### Conclusion - From the balanced reaction, we see that a total of 6 moles of electrons are transferred when 1 mole of \( \text{Cr}_2\text{O}_7^{2-} \) oxidizes \( \text{Fe}^{2+} \) to \( \text{Fe}^{3+} \). Thus, the answer is **6 moles of electrons**. ---

To determine how many total moles of electrons are transferred when 1 mole of \( \text{Cr}_2\text{O}_7^{2-} \) oxidizes \( \text{Fe}^{2+} \) to \( \text{Fe}^{3+} \) in acidic medium, we can follow these steps: ### Step 1: Identify the oxidation states - The oxidation state of chromium in \( \text{Cr}_2\text{O}_7^{2-} \) can be calculated as follows: \[ 2x + 7(-2) = -2 \implies 2x - 14 = -2 \implies 2x = 12 \implies x = +6 \] So, the oxidation state of chromium in \( \text{Cr}_2\text{O}_7^{2-} \) is +6. ...
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Knowledge Check

  • How many faradays are required to reduce 1 mole of Cr_(2)O_(7)^(2-) " to "Cr^(3+) in acid medium ?

    A
    2
    B
    3
    C
    5
    D
    6
  • How many coulombs of electricity is required to reduce 1 mole of Cr_2O_7^(2-) in acidic medium?

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    C
    2 x 96500 C
    D
    1 x 96500 C
  • How many Faradays are required to reduce 1 mol of Cr_2O_7^(2-) to Cr^(3+) in acidic medium?

    A
    2
    B
    3
    C
    5
    D
    6
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