Henry's law is not valid when

Options

A. Temperature is high
B. Pressure is low
C. The gas is not highly soluble
D. The gas neither reacts chemically with solvent nor dissociates or associates in the solvent

Answer

To determine when Henry's law is not valid, we need to analyze the conditions under which this law applies. Henry's law states that the amount of gas that dissolves in a liquid at a given temperature is directly proportional to the partial pressure of that gas above the liquid.

### Step-by-Step Solution:

1. **Understand Henry's Law**:
Henry's law is expressed mathematically as:
\[ C = k_H \cdot P \]
where \( C \) is the concentration of the dissolved gas, \( k_H \) is Henry's law constant, and \( P \) is the partial pressure of the gas.

2. **Identify Valid Conditions**:
For Henry's law to be valid, certain conditions must be met:
- The gas should be soluble in the solvent.
- The system should be at a relatively low pressure.
- The temperature should be constant and not too high.

3. **Determine When Henry's Law Fails**:
Henry's law is not valid under the following conditions:
- **High Temperature**: At high temperatures, gases tend to have lower solubility in liquids, which can lead to deviations from Henry's law.
- **High Pressure**: At high pressures, the behavior of gases can become non-ideal, and the proportionality may not hold.
- **Low Solubility**: If the gas is not highly soluble in the solvent, Henry's law does not apply effectively.

4. **Conclusion**:
Based on the analysis, Henry's law is not valid when the gas is not highly soluble in the solvent. Therefore, the correct answer to the question is that Henry's law is not valid when the gas is not highly soluble.

### Final Answer:
Henry's law is not valid when the gas is not highly soluble.