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CAIE A-Level Chemistry AS 7.1.8 The Quantities Present At Equilibrium Questions

Practise calculating equilibrium amounts, concentrations, mole fractions and partial pressures using CAIE 9701 AS questions and mark schemes.

Syllabus
2028–2030
Course
Chemistry 9701
Level
AS

Exam points

  • Calculate the quantities of substances present in an equilibrium mixture.

CAIE A-Level Chemistry AS 7.1.8 The Quantities Present At Equilibrium Questions question 1

[Maximum number: 1]

The reaction between sulfur dioxide and oxygen is reversible.

2SO2( g)+O2( g)⇌2SO3( g)Kc=280 mol−1dm3 at 1000 K2 \mathrm{SO}_{2}(\mathrm{~g})+\mathrm{O}_{2}(\mathrm{~g}) \rightleftharpoons 2 \mathrm{SO}_{3}(\mathrm{~g}) \quad K_{\mathrm{c}}=280 \mathrm{~mol}^{-1} \mathrm{dm}^{3} \text { at } 1000 \mathrm{~K}

In an equilibrium mixture at 1000 K the sulfur trioxide concentration is 6.00 moldm−36.00 \mathrm{~mol} \mathrm{dm}^{-3}.
The sulfur dioxide concentration is twice the oxygen concentration.
What is the sulfur dioxide concentration?

A

0.175 moldm−30.175 \mathrm{~mol} \mathrm{dm}^{-3}

B

0.252 moldm−30.252 \mathrm{~mol} \mathrm{dm}^{-3}

C

0.318 moldm−30.318 \mathrm{~mol} \mathrm{dm}^{-3}

D

0.636 moldm−30.636 \mathrm{~mol} \mathrm{dm}^{-3}

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