Poison for platinum, a catalyst in contact process of `H_2 SO_4` is ___.

Answer

To solve the question regarding the poison for platinum, a catalyst in the contact process of H₂SO₄, we can follow these steps:

### Step 1: Understand the Contact Process
The contact process is a method used to produce sulfuric acid (H₂SO₄) from sulfur dioxide (SO₂) and oxygen (O₂). In this process, platinum is commonly used as a catalyst to speed up the reaction.

**Hint:** Recall that the contact process involves the conversion of sulfur dioxide and oxygen into sulfur trioxide, which is then converted to sulfuric acid.

### Step 2: Identify the Role of Platinum
Platinum serves as a catalyst in the contact process. Catalysts are substances that increase the rate of a chemical reaction without being consumed in the process. However, catalysts can be poisoned by certain substances, which can inhibit their catalytic activity.

**Hint:** Think about what might interfere with the effectiveness of a catalyst.

### Step 3: Determine the Poison for Platinum
In the context of the contact process, it is known that arsenic oxide (As₂O₃) can act as a catalyst poison. When arsenic oxide is present, it reduces the catalytic activity of platinum, making it less effective in facilitating the reaction.

**Hint:** Recall that substances that reduce the effectiveness of catalysts are referred to as catalytic poisons.

### Step 4: Conclude the Answer
Based on the information gathered, the poison for platinum in the contact process of H₂SO₄ is arsenic oxide (As₂O₃).

**Final Answer:** The poison for platinum, a catalyst in the contact process of H₂SO₄, is As₂O₃ (arsenic oxide).

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