Equilibria (3.1.6-Phys.) Flashcards Preview

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Flashcards in Equilibria (3.1.6-Phys.) Deck (12)
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1
Q

Define dynamic equilibria

A

1) Forward and backward reactions occur at the same rate

2) The concentration of all reactants and products are constant

2
Q

State Le Chatalier’s principle

A

If a closed system at equilibrium is subject to a change, the position of equilibrium shifts to oppose the change.

3
Q

Define homogeneous

A

All reactants and products in the same phase

4
Q

The Contact Process:
2SO₂(g) + O₂(g) ⇌ 2SO₃(g)
What happens to the yield when you increase pressure?

A

The system will oppose this change by shifting the position of equilibrium in the forward direction, as there are fewer moles of gas. Therefore the yield increases.

5
Q

The Contact Process:
2SO₂(g) + O₂(g) ⇌ 2SO₃(g) (exothermic)
What happens to the yield when you increase temperature?

A

The system will oppose the increase in temperature by shifting the position of equilibrium in the backward direction because the endothermic direction. Therefore the yield decreases.

6
Q

Compromise temperature for…

2SO₂(g) + O₂(g) ⇌ 2SO₃(g)

A

Rate: increases
Yield: decreases
Compromise: medium temperature- acceptable yield and fast rate

7
Q

Compromise pressure for…

2SO₂(g) + O₂(g) ⇌ 2SO₃(g)

A

Rate: Increases
Yield: increases
Compromises: medium pressure, because high pressure equipment is expensive to build and maintain

8
Q

Kc expression for the reaction A + B —–> C + 2D

A

[C] x [D]² / [A] x [B]

9
Q

Units of [X] =?

A

mol dm⁻³

10
Q

What is the only factor that affects Kc?

A

A change in temperature

11
Q

How do you calculate Kc with a given volume (v)?

A

[mol of C/v] x [mol of D/v] / [mol of A/v] x [mol of B/vol]

12
Q

What is the effect of a catalyst on a system at equilibrium?

A

No effect because the catalyst increases the rate of reaction in both the forward and backward reactions equally.