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AceDSE · 试卷 · 2026.07

化學
Chemistry

Multi-stage Calculation and Practical Reasoning Test

分钟80 分钟
分40 分
应考部分English
考生姓名
日期

样本依据

the 36-page official Paper 1/2 sample: linked calculations, apparatus/graph interpretation, equilibrium, energetics and organic routes

本卷范围

A compressed compulsory/elective crossover test. It complements the two expanded Chemistry practice files previously produced.

考生须知

  1. Answer all questions and show working.
  2. Use molar gas volume 24.0 dm³ mol⁻¹ at room conditions and Faraday constant 96 500 C mol⁻¹.
  3. Structural formulae must show unambiguous connectivity.

Question 1 — Electrolysis

10 分
1(a)
A current of 0.750 A passes through aqueous copper(II) sulfate using inert electrodes for 16.0 min. Calculate the mass of copper deposited.
[5 分]
1(b)
Calculate the volume of gas formed at the anode at room conditions and state one observation at each electrode.
[5 分]

Question 2 — Equilibrium

10 分
2(a)
0.0400 mol N₂O₄ is placed in a 2.00 dm³ vessel. At equilibrium, 40.0% has dissociated according to N₂O₄(g) ⇌ 2NO₂(g). Calculate Kc with units.
[6 分]
2(b)
The vessel volume is suddenly halved at constant temperature. Describe the immediate change and the subsequent shift. Explain why Kc is unchanged.
[4 分]

Question 3 — Calorimetry

10 分
3(a)
0.120 g Mg is added to 50.0 cm³ of 1.00 mol dm⁻³ HCl. The maximum temperature rise is 11.8°C. Taking density as 1.00 g cm⁻³ and c=4.18 J g⁻¹ K⁻¹, calculate the experimental molar enthalpy change. Include the magnesium mass in the heated mass.
[6 分]
3(b)
The accepted value is more negative. Explain the direction of this discrepancy and describe two improvements addressing different errors.
[4 分]

Question 4 — Organic analysis and synthesis

10 分
4(a)
Compound X has molecular formula C₄H₈O₂. Its IR spectrum has a strong absorption near 1740 cm⁻¹ but no broad O–H absorption. Hydrolysis gives methanol and propanoic acid. Deduce X and explain each piece of evidence.
[5 分]
4(b)
Give reagents and conditions to prepare X from the two hydrolysis products. Starting with 7.40 g propanoic acid and excess methanol, 6.16 g X is isolated. Calculate percentage yield.
[5 分]

所有题目及图表均为 AceDSE 原创；官方样本只用于校准形式、难度及思考层次。
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