10. Equilibrium constant Kp Flashcards Preview

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Flashcards in 10. Equilibrium constant Kp Deck (22)
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1

What is Kp?

The equilibrium constant for a reversible reaction where some or all of the reactants and products are gases

2

Why do solids, liquids and aqueous solutions not appear in the expression for Kp?

They don't contribute to the pressure of a system

3

What substances appear in the expression for Kp?

Gases only

4

What is the expression for Kp when aA + bB ⇋ cC + dD?

p(C)ᶜ p(D)ᵈ / p(A)ᵃ p(B)ᵇ

5

In the expression for Kp, what does the p before the brackets stand for?

Partial pressure

6

How are the units for Kp worked out?

The same way as those for Kc

7

What can be used the same way as Kc to calculate the composition of an equilibrium mixture?

The gas equilibrium expression

8

What is the mole fraction?

The proportion of gaseous mixture that is made up of one particular gas

9

How to calculate the mole fraction of a gas in a mixture?

Number of moles of a gas / Total number of moles of gas in the mixture

10

What is partial pressure (p)?

In an equilibrium reaction involving gases, when each individual gas exerts its own pressure

11

How to calculate the partial pressure of a gas in a mixture?

Mole fraction of gas x Total pressure of the mixture

12

How to calculate total pressure of a gas mixture?

Sum of all partial pressures of each gas in the reaction

13

What is Le Chatelier's principle?

If a factor affecting the position of equilibrium is altered, the position of equilibria will shift to oppose the effect of the change

14

What happens to equilibrium if the temperature is decreased?

It will shift in the direction of the exothermic reaction

15

What happens to equilibrium if the temperature is increased?

It will shift in the direction of the endothermic reaction

16

What happens to Kp if a change in temperature shifts the position of equilibrium to the right?

Kp will increase

17

What happens to Kp if a change in temperature shifts the position of equilibrium to the left?

Kp will decrease

18

What happens to equilibrium if the pressure is increased?

It will shift in the direction with the least moles of gas

19

What happens to equilibrium if the pressure is decreased?

It will shift in the direction with the most moles of gas

20

Does changing pressure make any difference to Kp?

No

21

Does adding a catalyst have any effect on Kp?

No

22

Why does adding a catalyst have no effect on Kp?

Increases rate of forward and reverse reactions by the same amount - so position of equilibrium will be reached quicker but remain unchanged