The value of the ionic product of water depends

Options

A. on volume of water
B. on temperature
C. changes on adding acid or alkali
D. always remain constant

Explanation

To determine what the value of the ionic product of water depends on, we can follow these steps:

### Step 1: Understand the Definition of Ionic Product of Water
The ionic product of water (Kw) is defined as the product of the molar concentrations of hydrogen ions (H⁺) and hydroxide ions (OH⁻) in water. Since H⁺ ions exist as hydronium ions (H₃O⁺) in solution, we can express Kw as:
\[ K_w = [H_3O^+][OH^-] \]

### Step 2: Recognize the Constant Nature of Kw
The value of Kw is constant at a given temperature. At 25°C (298 K), the value of Kw is approximately:
\[ K_w = 1.008 \times 10^{-14} \]
For simplicity, it is often approximated as:
\[ K_w \approx 1.0 \times 10^{-14} \]

### Step 3: Identify the Dependence on Temperature
Kw is only constant at a specific temperature. If the temperature changes, the value of Kw will also change. This is because the degree of dissociation of water molecules into H⁺ and OH⁻ ions increases with temperature. As temperature rises, more water molecules dissociate, leading to an increase in the concentrations of H⁺ and OH⁻ ions.

### Step 4: Conclude the Factors Affecting Kw
From the above analysis, we conclude that the ionic product of water depends solely on temperature. It does not depend on the volume of water, the addition of acids or bases, or other factors.

### Final Answer
The value of the ionic product of water depends on temperature.

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