Kp

Question 1

Partial pressure of a gas in a mixture =

Answer 1

mole fraction of a gas x total pressure

Question 2

Why does the Kp in a certain reaction not have any units

Answer 2

There are the same number of moles on both sides of the equation so the total pressure cancels

Question 3

mole fraction =

Answer 3

moles of one component at equilibrium / total moles of all gaseous components at equilibrium

Question 4

How to calculate Kp

Answer 4

Write down the equation
Write down the initial moles of each gaseous component
Write down the equilibrium moles
Calculate the total moles of gas at equilibrium
Calculate the partial pressure
Kp = p(products) / p(reactants)

Question 5

An experiment was carried out to determine the Kp and was then repeated on different days. Justify whether this would improve the reliability of the data collected.

Answer 5

It would not improve the reliability because the temperature may vary causing the value of Kp to change as the value of Kp changes with temperature.

Question 6

Suggest why ammonium nitrate is not included in the expression for Kp

Answer 6

It is a solid and solids have no partial pressure so will therefore not be included in the expression for Kp

Question 7

4NH3 + 5O2 = 4NO + 6H20
State and explain the effect on the value of Kp and hence on the position of equilibrium if the pressure is increased

Answer 7

The value of Kp does not change.
When the pressure increases, the value of (Kp expression) increases.
The quotient is now greater than unchanged Kp, so the quotient must decrease. This happens if more reactants are being formed and less products, so the position of equilibrium moves to the left to decrease the quotient until it equals Kp again.