ESAT ESAT Chemistry 2 — Questions and Answers
Question 1: What does Le Chatelier's Principle state in chemical equilibrium?
- A system at equilibrium will shift to oppose any imposed change (Correct answer)
- Equilibrium always favours the forward reaction
- Catalysts shift equilibrium to the right
- Temperature has no effect on equilibrium position
Correct answer: A system at equilibrium will shift to oppose any imposed change
Le Chatelier's Principle states that a system at equilibrium responds to a stress by shifting to minimise that stress.
Question 2: In ESAT Chemistry, what is the first ionisation energy?
- Energy to remove one electron from a gaseous atom (Correct answer)
- Energy released when one electron is gained
- Energy to break one mole of bonds
- Energy required to melt one mole of a substance
Correct answer: Energy to remove one electron from a gaseous atom
First ionisation energy is the energy needed to remove one mole of electrons from one mole of gaseous atoms.
Question 3: What shape does a molecule with 4 bonding pairs and no lone pairs adopt?
- Tetrahedral (Correct answer)
- Trigonal planar
- Linear
- Bent
Correct answer: Tetrahedral
VSEPR theory predicts a tetrahedral geometry for 4 bonding pairs with no lone pairs (e.g., CH₄).
Question 4: Which functional group characterises an alcohol?
- -OH (hydroxyl) (Correct answer)
- -COOH (carboxyl)
- -NH₂ (amino)
- -CHO (aldehyde)
Correct answer: -OH (hydroxyl)
Alcohols contain the -OH (hydroxyl) functional group attached to a carbon atom.
Question 5: What is Avogadro's constant?
- 6.022 × 10²³ mol⁻¹ (Correct answer)
- 6.022 × 10²² mol⁻¹
- 1.38 × 10⁻²³ mol⁻¹
- 9.81 × 10²³ mol⁻¹
Correct answer: 6.022 × 10²³ mol⁻¹
Avogadro's constant is 6.022 × 10²³ mol⁻¹, the number of particles in one mole.
Question 6: What type of reaction converts alkenes to alkanes using hydrogen gas?
- Hydrogenation (Correct answer)
- Halogenation
- Hydrolysis
- Oxidation
Correct answer: Hydrogenation
Hydrogenation adds H₂ across the double bond of an alkene, converting it to an alkane.
ESAT ESAT Chemistry 2
What does Le Chatelier's Principle state in chemical equilibrium?