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IB DP Chemistry Mock Exam HL Paper 1A Set 4 - 2025 Syllabus

IB DP Chemistry Mock Exam HL Paper 1A Set 4

Prepare for the IB DP Chemistry Exam with our comprehensive IB DP Chemistry Exam Mock Exam HL Paper 1A Set 4. Test your knowledge and understanding of key concepts with challenging questions covering all essential topics. Identify areas for improvement and boost your confidence for the real exam

IB DP Chemistry Mock Tests -All Sets

Question 

What impact does doubling the pressure have on the equilibrium, assuming all other conditions stay the same?
.
\( 2SO_2(g) + O_2(g) \rightleftharpoons 2SO_3(g) \)
Effect on equilibrium positionEffect on equilibrium constant, \( K \)
(A)                            shifts rightno change
(B)                            shifts leftno change
(C)                           shifts rightincreases
(D)                           shifts leftdecreases
▶️ Answer/Explanation
Detailed solution

Reaction: 3 moles gas → 2 moles gas.
Increasing pressure shifts equilibrium to the side with fewer gas moles → shifts right.
Equilibrium constant \(K\) depends only on temperature, not pressure → no change.
✅ Answer: (A)

Question 

Which solution has a pH of 9.0?
(A) \(10^{-9} \ \text{mol dm}^{-3} \ \text{NH}_3(\text{aq})\)
(B) \(10^{-9} \ \text{mol dm}^{-3} \ \text{NaOH}(\text{aq})\)
(C) \(10^{-5} \ \text{mol dm}^{-3} \ \text{NH}_3(\text{aq})\)
(D) \(10^{-5} \ \text{mol dm}^{-3} \ \text{NaOH}(\text{aq})\)
▶️ Answer/Explanation
Detailed solution

pH = 9.0 ⇒ pOH = 5.0 ⇒ [OH⁻] = \(10^{-5} \ \text{mol dm}^{-3}\).
Strong base NaOH at \(10^{-5} \ \text{M}\) gives [OH⁻] = \(10^{-5} \ \text{M}\) ⇒ pH = 9.0.
Weak base NH₃ at same concentration gives [OH⁻] less than \(10^{-5} \ \text{M}\) ⇒ pH < 9.
✅ Answer: (D)

Question 

Which indicator is most suitable for the titration of phenylamine with nitric acid?
(A) Bromophenol blue, pKa = 4.2
(B) Bromothymol blue, pKa = 7.0
(C) Phenol red, pKa = 7.9
(D) Phenolphthalein, pKa = 9.6
▶️ Answer/Explanation
Detailed solution

Phenylamine is a weak base, nitric acid is a strong acid.
Equivalence point pH < 7 (acidic).
Choose indicator with pKa near equivalence point pH.
Bromophenol blue (pKa = 4.2) changes color around pH 3.0–4.6, suitable for acidic equivalence point.
✅ Answer: (A)

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