ECAT Chemistry — Chemical Equilibrium
Chemical Equilibrium is part of the Chemistry section of the UET ECAT (30 of the 100 MCQs). It breaks into 3 subtopics, and we hold 37 ECAT-pattern practice MCQs on it, each with a written explanation. Tap a subtopic below to practise just that.
Subtopics (3)
How Chemical Equilibrium is tested
Across the 7 ECAT past papers on ParhaiKrlo, Chemical Equilibrium accounts for 7 questions. It appears in 4 of them, about 1.8 questions a paper. The heaviest was ECAT Past Paper 03, with 3 questions, and the most recent is ECAT Past Paper 07, with 1.
| Paper | Questions |
|---|---|
| ECAT Past Paper 07 | 1 |
| ECAT Past Paper 04 | 2 |
| ECAT Past Paper 03 | 3 |
| ECAT Past Paper 01 | 1 |
Chemical Equilibrium MCQs from the ECAT past papers
Try each one before opening the answer. Each comes with a short explanation.
- Q1 · ECAT Past Paper 07 · Chemical Equilibrium
For CO(g) + H₂O(g) ⇌ CO₂(g) + H₂(g), ΔH = −41.84 kJ/mol, if heat is applied at equilibrium:
- A.More CO₂ and H₂ are produced to compensate for the temperature change
- B.The reaction moves in the backward direction to compensate
- C.No change takes place
- D.The reaction stops
Show answer
Answer: B. The reaction moves in the backward direction to compensate — The forward reaction is exothermic; adding heat favours the endothermic (backward) direction.
- Q2 · ECAT Past Paper 04 · Chemical Equilibrium
Poly(tetrafluoroethene) is used as a non-stick coating and for replacement bone joints. One stage in making it is 2CHClF₂(g) ⇌ C₂F₄(g) + 2HCl(g), ΔH = +125 kJ mol⁻¹. Which condition will shift this equilibrium to the right?
- A.High temperature
- B.High pressure
- C.Using a catalyst
- D.All of the above
Show answer
Answer: A. High temperature — The forward reaction is endothermic, so raising the temperature favours it. (It also increases gas moles, so high pressure would shift it left; a catalyst does not shift it.)
- Q3 · ECAT Past Paper 03 · Chemical Equilibrium
When a small amount of an acid or a base is added to a buffer solution, its pH:
- A.Changes drastically
- B.Does not change at all
- C.Changes rapidly
- D.Changes a little
Show answer
Answer: D. Changes a little — A buffer resists change: its pH changes only slightly.