Question

A gas exerts a pressure of 0.74 atm in a certain container. Suddenly, a chemical change occurs that consumes half of the molecules originally present and forms two new molecules for every three consumed. Determine the new pressure in the container if the volume of the container and the temperature are unchanged. The reaction that occurs is: 3A(g) —> 2B(g)

Answer 1

• 0.49 atm

Step-by-step explanation:

When the volume and temperature of a gas are unchanged, the pressure is directly related to the number of molecules, this is:

`p=Kn`

Or:

`(p_1)/(n_1)=(p_2)/(n_2)`

Thus:

`p_2=p_1* (n_2)/(n_1)`

For the reaction 3A(g) → 2B(g), n₁ = 3 and n₂ = 2.

Then:

`p_2=0.74atm* (2)/(3)\approx0.49atm`

As you see, the pressure decreases, because the number of molecules decreases.