Question

To an equilibrium mixture of $2 SO _{2(g)}+ O _{2(g)} \rightleftharpoons 2 SO _{3(g)}$ some helium, an inert gas, is added at constant volume. The addition of helium causes the total pressure to double, which of the following is true?

• A. The concentration of all three gases is unchanged
• B. The concentration of sulphur trioxide increases
• C. The number of moles of sulphur trioxide increases
• D. The concentration of sulphur dioxide increases

Answer 1

Answer: (A)

The concentration of all three gases is unchanged

Answer 2

Since, the inert gas is added at constant volume, ie, the volume is not allowed to increase, the concentrations of all the three gases remain unchanged.