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Edexcel IAL Chemistry 9.1 Collision theory and rate factors

Identify which factor changed, state its particle-level effect and link that change to more or fewer successful collisions per unit time without altering final yield unless…

Syllabus
First assessment 2019
Course
Chemistry YCH11
Level
AS

Exam points

  • Explain concentration or pressure effects through particles per volume and collision frequency.
  • Explain surface-area effects through more exposed particles and collision opportunities.
  • Separate a faster initial rate from unchanged final product when reacting amounts are fixed.

9.1—Understand, in terms of the collision theory, the effect of changes in concentration, temperature, pressure and surface area question 1

[Maximum number: 1]

Ammonium nitrate, NH4NO3\mathrm{NH}_{4} \mathrm{NO}_{3}, is used in the manufacture of fertilisers and explosives. It is produced on a large scale using only methane, water and air.
The process has four stages.

In Stage 3, nitrogen monoxide, NO, is produced in the reaction between NH3\mathrm{NH}_{3} (from Stage 2) and O2\mathrm{O}_{2} (from the air). The conditions used are a temperature of 1100 K in the presence of a platinum-rhodium catalyst.

4NH3( g)+5O2( g)⇌4NO( g)+6H2O( g)ΔH=−905 kJ mol−14 \mathrm{NH}_{3}(\mathrm{~g})+5 \mathrm{O}_{2}(\mathrm{~g}) \rightleftharpoons 4 \mathrm{NO}(\mathrm{~g})+6 \mathrm{H}_{2} \mathrm{O}(\mathrm{~g}) \quad \Delta H=-905 \mathrm{~kJ} \mathrm{~mol}^{-1}

Give one reason why a high temperature is needed in this reaction.

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