How many moles of iodine are liberated when 1 m potassium dichromate reacts with potassium iodide?

Options

A. 1
B. 2
C. 3
D. 4

Explanation

To determine how many moles of iodine are liberated when 1 mole of potassium dichromate (K₂Cr₂O₇) reacts with potassium iodide (KI), we need to follow these steps:

### Step 1: Write the balanced chemical equation
The reaction between potassium dichromate and potassium iodide in the presence of sulfuric acid (H₂SO₄) can be represented as follows:

\[ K_2Cr_2O_7 + 6 KI + 7 H_2SO_4 \rightarrow 3 I_2 + 2 Cr_2(SO_4)_3 + 7 H_2O + 6 K_2SO_4 \]

### Step 2: Identify the stoichiometry of the reaction
From the balanced equation, we can see that:
- 1 mole of K₂Cr₂O₇ reacts with 6 moles of KI to produce 3 moles of I₂ (iodine).

### Step 3: Determine the moles of iodine produced
Since the question asks how many moles of iodine are liberated when 1 mole of potassium dichromate reacts, we can directly refer to the balanced equation. According to the equation:
- 1 mole of K₂Cr₂O₇ produces 3 moles of I₂.

### Conclusion
Therefore, when 1 mole of potassium dichromate reacts with potassium iodide, **3 moles of iodine (I₂) are liberated**.

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