Answer:

7.1 atm

Explanation:

Step 1: Calculate Henry’s constant

At P = 3.5 atm, we can dissolve 1.2 g of a gas in 1.0 L of water, that is, the concentration is C = 1.2 g/1.0 L = 1.2 g/L. We can calculate Henry’s constant, which relates the concentration and the pressure of a gas dissolving in a liquid, using Henry’s law.

C = k × P

k = C/P = (1.2 g/L)/3.5 atm = 0.34 g/L.atm

Step 2: Calculate the pressure needed to dissolve 2.4 g of the gas in 1.0 L of water

We want to dissolve 2.4 g of the gas in 1.0 L of water, that is, C = 2.4 g/1.0 L = 2.4 g/L. We can calculate the pressure required using Henry’s law.

C = k × P

P = C/k = (2.4 g/L)/(0.34 g/L.atm) = 7.1 atm