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Date November 2018 Marks available 1 Reference code 18N.2.sl.TZ0.5
Level SL Paper 2 Time zone TZ0
Command term State Question number 5 Adapted from N/A

Question

This reaction is used in the manufacture of sulfuric acid.

2SO2 (g) + O2 (g) 2SO3 (g)        Kc = 280 at 1000 K

State why this equilibrium reaction is considered homogeneous.

[1]
a.

0.200 mol sulfur dioxide, 0.300 mol oxygen and 0.500 mol sulfur trioxide were mixed in a 1.00 dm3 flask at 1000 K.

Predict the direction of the reaction showing your working.

[3]
b.

Markscheme

all «species» are in same phase ✔

 

Accept “all species are in same state”.

Accept “all species are gases”.

a.

«reaction quotient/Q =»  [ S O 3 ] 2 [ S O 2 ] 2 [ O 2 ] / 0.500 2 0.200 2 × 0.300 / 20.8

 

reaction quotient/Q/20.8/answer < Kc/280

OR

mixture needs more product for the number to equal Kc ✔

 

reaction proceeds to the right/products ✔

 

Do not award M3 without valid reasoning.

b.

Examiners report

[N/A]
a.
[N/A]
b.

Syllabus sections

Core » Topic 1: Stoichiometric relationships » 1.1 Introduction to the particulate nature of matter and chemical change
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Core » Topic 1: Stoichiometric relationships
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