1How does increasing temperature affect the equilibrium constant Kc?
- for exothermic reactions increasing temprature decreases Kc
-For endothermic reactions: increasing temprature increases Kc
2How does decreasing temperature affect the equilibrium constant Kc?
- for exothermic reactions decreasing temprature increases Kc
-For endothermic reactions: decreasing temprature decreases Kc
3how does pressure affect the Kc?
pressure changes do not affect Kc - they only affect the position of equilibrium
4Do the effects of pressure/ teprature differ between homogeneous and heterogeneous equilibria?
No — the same principles apply, but for heterogeneous systems, only gaseous or aqueous species are affected by pressure or concentration changes.
5What is the equation linking total entropy change and the equilibrium constant?
ΔS₍total₎ = R ln K
6What is ΔS₍total₎ in terms of system and surroundings?
ΔS₍total₎ = ΔS₍system₎ + ΔS₍surroundings₎
7How does temperature affect ΔS₍surroundings₎?
ΔS₍surroundings₎ = −ΔH / T → as temperature increases, |ΔS₍surroundings₎| decreases (becomes smaller in magnitude).
8How does increasing temperature affect ΔS₍total₎ for an exothermic reaction?
ΔH is negative → ΔS₍surroundings₎ positive at low T → as T increases, ΔS₍surroundings₎ decreases → ΔS₍total₎ decreases.
9How does increasing temperature affect ΔS₍total₎ for an endothermic reaction?
ΔH is positive → ΔS₍surroundings₎ negative → as T increases, this negative value becomes smaller (less negative) → ΔS₍total₎ increases.
10Q: What happens to K when ΔS₍total₎ increases?
A: From ΔS₍total₎ = R ln K → K increases.
11Q: What happens to K when ΔS₍total₎ decreases?
A: ln K decreases → K decreases.
12Q: What does the equilibrium constant (K) show about a reaction?
A: It shows the extent to which a reaction goes to completion — how much product is formed compared to reactants at equilibrium.
13Q: What does a K value (≫1) mean?
The equilibrium lies far to the right → mostly products present → reaction almost goes to completion.
14Q: What does a K value (<1) mean?
A: The equilibrium lies far to the left → mostly reactants present → reaction barely proceeds.
15Q: What does K ≈ 1 indicate?
A: Significant amounts of both reactants and products are present → equilibrium lies roughly in the middle.
16Q: What does K = 0 or extremely small mean in practice?
A: The reaction does not occur to any significant extent — products hardly form.
17what is the expression to find ln k
ln K = ΔS₍total₎ / R
18Why does increasing the temprature decrease the KC value
the equilibrium shifts to the reactant side, reducing the concentration of products and therefore giving a smaller Kc value.
19For a reaction at a given moment:
- Qc > Kc
-Qc < Kc
- Qc = Kc
Qc > Kc (too much product is formed, equilibrium shift left)
Qc < Kc (too much reactant, equilibrium shift right)
Qc = Kc (equal amount of product & reactant, no shift)