ESAT 2025 Chemistry Esat.fyi Chemistry
10 questions10 marks20Updated August 2026
The ESAT 2025 Chemistry Esat.fyi Chemistry paper in full: all 10 questions, each with its answer. ESAT is the Engineering and Science Admissions Test. Sit it cold under exam timing, mark it, then work back through anything you missed using the solutions below.
Questions and answers are free. Full step-by-step worked solutions unlock with a free account. Start practising.
Question 1
1 mark5.6 g of a metal M (relative atomic mass 56) reacts completely with chlorine gas. Exactly 3.6 dm³ of Cl₂, measured at room temperature and pressure (molar volume 24 dm³), is used. What is the formula of the chloride?
- A.MCl
- B.MCl₂
- C.MCl₃
- D.M₂Cl₃
- E.M₃Cl
- F.M₂Cl
Answer: C
Question 2
1 mark200 cm³ of 0.50 mol dm⁻³ hydrochloric acid is added to 3.0 g of calcium carbonate (Mr 100), which reacts completely: CaCO₃ + 2HCl → CaCl₂ + CO₂ + H₂O. The mixture is then made up to 1.0 dm³ with water. What is the pH of the final solution? (log 4 ≈ 0.60)
- A.1.2
- B.1.4
- C.1.7
- D.2.4
- E.3.4
- F.7.0
Answer: B
Question 3
1 markWhat is the total amount, in moles, of ions present in 250 cm³ of 0.20 mol dm⁻³ aluminium sulfate solution, Al₂(SO₄)₃?
- A.0.05
- B.0.10
- C.0.15
- D.0.25
- E.0.50
- F.1.0
Answer: D
Question 4
1 markEthanol (Mr 46) is fully oxidised to ethanoic acid by acidified potassium dichromate(VI). Each ethanol molecule loses 4 electrons and each dichromate ion Cr₂O₇²⁻ gains 6 electrons. What volume of 0.20 mol dm⁻³ dichromate solution is required to oxidise 0.69 g of ethanol?
- A.12.5 cm³
- B.25.0 cm³
- C.33.3 cm³
- D.50.0 cm³
- E.75.0 cm³
- F.100 cm³
Answer: D
Question 5
1 markA reservoir holds 1.9 × 10⁶ dm³ of water (density 1.0 kg dm⁻³). It currently contains fluoride ions at 0.30 ppm; the target is 1.30 ppm. What mass of sodium fluoride, NaF (Mr 42), must be added? (F = 19; 1 ppm = 1 mg per kg of water.)
- A.1.9 kg
- B.4.2 kg
- C.5.5 kg
- D.8.4 kg
- E.2.1 kg
- F.42 kg
Answer: B
Question 6
1 mark2.0 mol of propane, C₃H₈, is burned in a limited supply of oxygen. The carbon-containing products are carbon dioxide and carbon monoxide in equal amounts (equal moles), and water is the only other product. How many moles of O₂ are used?
- A.5.0
- B.7.0
- C.8.5
- D.10.0
- E.12.5
- F.17
Answer: C
Question 7
1 markAn acid contains 9.0 g of the acid per dm³ in a 0.10 mol dm⁻³ solution. In a titration, 25.0 cm³ of this acid is exactly neutralised by 50.0 cm³ of 0.10 mol dm⁻³ sodium hydroxide. The acid also fizzes when magnesium is added. Consider: (1) the acid is diprotic; (2) the acid is a strong acid; (3) the relative formula mass of the acid is 90. Which statement(s) is/are correct?
- A.none
- B.1 only
- C.2 only
- D.3 only
- E.1 and 2
- F.1 and 3
- G.2 and 3
- H.1, 2 and 3
Answer: F
Question 8
1 markFor the reaction C₂H₄ + H₂ → C₂H₆, ΔH = −130 kJ mol⁻¹. Using bond energies H–H = 436, C–C = 348 and C=C = 612 kJ mol⁻¹, what is the mean C–H bond energy, in kJ mol⁻¹?
- A.350
- B.385
- C.415
- D.435
- E.465
- F.830
Answer: C
Question 9
1 markFour metals P, Q, R, S are used to build simple cells. The voltages are: P–Q = 0.62 V (P is the negative electrode); Q–S = 0.30 V (Q negative); R–S = 1.24 V (R negative). The more reactive metal is always the negative electrode. Which row lists the metals from MOST to LEAST reactive?
- A.P, R, Q, S
- B.R, P, Q, S
- C.R, P, S, Q
- D.P, Q, R, S
- E.S, Q, P, R
- F.R, Q, P, S
Answer: B
Question 10
1 markA 0.50 dm³ solution contains 0.80 mol dm⁻³ copper(II) sulfate. Using inert graphite electrodes, electrolysis deposits 6.4 g of copper at the cathode (Cu = 64). The solution is then made back up to 0.50 dm³. What is the final concentration of copper(II) ions, in mol dm⁻³?
- A.0.10
- B.0.30
- C.0.60
- D.0.70
- E.0.80
- F.1.20
Answer: C