IB DP Chemistry HL Prediction Paper 1A and 1B

IB DP Chemistry HL Prediction Paper 1A and 1B- April/May 2025 Exam

IB DP Chemistry HL Prediction Paper 1A and 1B: Prepare for the IB exams with subject-specific Prediction questions, model answers. All topics covered.

Prepared by IB teachers: Access our IB DP Chemistry SL Prediction Paper 1 with model answer. Students: Practice with exam-style papers for IB DP Chemistry SL Exam

Question 1

What do all greenhouse gases have in common?

A. They are emitted by the burning of fossil fuels. B. They absorb ultraviolet radiation. C. They are symmetrical molecules with no polar bonds. D. They absorb infrared radiation.

▶️ Answer/Explanation

Answer: D

Explanation: Greenhouse gases (e.g., CO₂, CH₄, H₂O) absorb infrared radiation emitted by the Earth’s surface, trapping heat in the atmosphere. While some are emitted by fossil fuels (A), this is not universal (e.g., water vapor). They do not absorb UV radiation (B), and many have polar bonds (C).

Question 2

Which is the mass spectrum of butanal?

▶️ Answer/Explanation

Answer: C

Explanation: Butanal (C₄H₈O) shows a molecular ion peak (M⁺) at m/z = 72 and a characteristic fragment at m/z = 44 due to the loss of C₂H₄ (44 = CHO⁺). The other options represent fragments unlikely for butanal.

Question 3

A student determined the enthalpy change of combustion of a fuel by burning it in a spirit burner placed under a metal can containing 100 cm3 of water.

Which modification can improve the accuracy of the experiment?

A. Placing a lid on the metal can containing water B. Covering the spirit burner with aluminium foil C. Increasing the distance between the metal can and the spirit burner D. Using warm water instead of water at room temperature in the metal can

▶️ Answer/Explanation

Answer: A. Placing a lid on the metal can containing water

Explanation:

Accuracy in a calorimetry experiment improves by minimizing heat loss to the surroundings.
A. Placing a lid on the metal can: Reduces evaporation and heat loss to the air, improving accuracy.
B. Covering the spirit burner: Would extinguish the flame or reduce heat transfer, decreasing accuracy.
C. Increasing the distance: Reduces heat transfer to the water, lowering accuracy.
D. Using warm water: Introduces an initial temperature variation, reducing accuracy.
Option A: Correct. Minimizes heat loss, enhancing accuracy.
Option B: Incorrect. Hinders the experiment.
Option C: Incorrect. Decreases heat transfer efficiency.
Option D: Incorrect. Alters initial conditions unfavorably.

Scientific Context:
This question relates to experimental design in calorimetry, covered in IB Chemistry (Topic 1: Measurement and Data Processing).

IB DP Chemistry HL Prediction Paper 1A and 1B

IB DP Chemistry HL Prediction Paper 1A and 1B for 2025 Exams