DP Chemistry (last assessment 2024)

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Question 19M.2.hl.TZ2.2c(i)

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Date May 2019 Marks available [Maximum mark: 1] Reference code 19M.2.hl.TZ2.2c(i)
Level hl Paper 2 Time zone TZ2
Command term Deduce Question number c(i) Adapted from N/A
c(i).
[Maximum mark: 1]
19M.2.hl.TZ2.2c(i)

The thermal decomposition of dinitrogen monoxide occurs according to the equation:

2N2O (g) → 2N2 (g) + O2 (g)

The reaction can be followed by measuring the change in total pressure, at constant temperature, with time.

The x-axis and y-axis are shown with arbitrary units.

This decomposition obeys the rate expression:

− d [ N 2 O] d t = k[N2O]

(c(i))

Deduce how the rate of reaction at t = 2 would compare to the initial rate.

[1]

Markscheme

half «of the initial rate»    [✔]

 

Note: Accept “lower/slower «than initial rate»”.

Examiners report

Though the differential equation was considered to be misleading by teachers, most candidates attempted to answer this question, and more than half did so correctly, considering they had the graph to visualize the gradient.

Syllabus sections