Question

The partial pressure of a gas at \(25^{\circ}\)C is \(0.18\) atm, calculate the concentration of the gas dissolved at the same temperature,
If \(K_H\) is \(0.15 \text{mol dm}^{-3} \text{atm}^{-1}\)

• A. \(0.027\) M
• B. \(1.8\) M
• C. \(4.5\) M
• D. \(0.45\) M

Hint:

Henry law: concentration = KH x partial pressure.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Henry's law says that the amount of a gas dissolved in a liquid is directly proportional to its partial pressure above the liquid.

Step 2: Key Formula:
\[ C = K_H \times P \]

Step 3: Substitute:
\(K_H = 0.15\) mol dm\(^{-3}\) atm\(^{-1}\) and \(P = 0.18\) atm.
\[ C = 0.15 \times 0.18 = 0.027 \text{ M} \]

Step 4: Why the other options are wrong.
1.8 M and 4.5 M are far too large. Dividing instead of multiplying gives \(0.18/0.15 = 1.2\), also wrong. 0.45 M comes from a decimal slip. The correct product is 0.027.

Final Answer:
The dissolved gas concentration is 0.027 M. \[ \boxed{\text{(A) }0.027\ \text{M}} \]