The Chemical Industry | OCR A-Level Chemistry B (Salters) (H433)

The Chemical Industry

250 questions
16 subtopics
The ten storylines, examined across all three papers
Component 01, Component 02 and Component 03

The storyline that carries kinetics and the quantitative treatment of equilibrium: rate equations and orders, half-lives, the Arrhenius equation, the rate-determining step, what changes an equilibrium constant, and the chemistry and economics of an industrial process..

It covers rate equations, order and the rate constant, deducing the units of k and rate calculations, half-lives, continuous monitoring, quenching and the initial rates method, reading order from concentration-time and rate-concentration graphs, the Arrhenius equation and what each symbol means, the ln k against 1/T plot and finding the activation enthalpy, rate-determining step and mechanism, effect of conditions on the magnitude of the equilibrium constant, economic operating conditions for an industrial process, writing a Kc expression and deducing its units, iCE-table calculations and measuring Kc experimentally, chemical reactions in industrial processes, nitrogen, ammonia and the ammonium ion, oxidation states of nitrogen and the tests for nitrate and ammonium and costs, benefits and risks of industrial processes.

Sample questions from The Chemical Industry

Answer each one closed book first, then open the answer.

Rate equations, order and the rate constant

Can the orders in a rate equation be predicted from the balanced equation?

Show the answer
No, orders can only be found by experiment, because they depend on the mechanism rather than on the overall stoichiometry.
Half-lives

Rearrange that relationship to give k in terms of the half-life.

Show the answer
k = ln2 ÷ t½.
Reading order from concentration-time and rate-concentration graphs

What shape of concentration–time graph indicates a zero-order reaction?

Show the answer
A straight line of constant negative gradient until the reactant runs out.
The ln k against 1/T plot and finding the activation enthalpy

An Arrhenius plot has a gradient of −6.50 × 10³ K. Calculate the activation enthalpy in kJ mol⁻¹.

Show the answer
Ea = 6.50 × 10³ × 8.314 = 5.40 × 10⁴ J mol⁻¹, which is 54.0 kJ mol⁻¹.
Effect of conditions on the magnitude of the equilibrium constant

What effect does a change of pressure have on the magnitude of Kc?

Show the answer
None; Kc is unchanged by pressure.
Writing a Kc expression and deducing its units

Deduce the units of Kc for N₂O₄(g) ⇌ 2NO₂(g).

Show the answer
Kc = [NO₂]² ÷ [N₂O₄], giving (mol dm⁻³)² ÷ mol dm⁻³, which is mol dm⁻³.
Chemical reactions in industrial processes

Given the equations S + O₂ → SO₂ and 2SO₂ + O₂ ⇌ 2SO₃, identify which stage is an equilibrium and what that implies.

Show the answer
The second stage is reversible, so conditions must be chosen to give an acceptable equilibrium yield of sulfur trioxide at a workable rate.
Oxidation states of nitrogen and the tests for nitrate and ammonium

Why is the name nitrate(V) used in preference to nitrate?

Show the answer
The Roman numeral states the oxidation state of nitrogen, distinguishing NO₃⁻ from the nitrate(III) ion, NO₂⁻.

The 16 subtopics

One subtopic is one session. Work down the list.

Subtopic	What it covers	Questions
Rate equations, order and the rate constant	Recall questions on the definition of rate and its units, what order means, and why the orders cannot be read off the balanced equation.	10
Deducing the units of k and rate calculations	Recall questions on working out the units of k for each overall order, and calculating a rate or a concentration from a rate equation.	16
Half-lives	Recall questions on which order has a constant half-life, how successive half-lives behave for each order, and k = ln 2 / t½.	22
Continuous monitoring, quenching and the initial rates method	Recall questions on the three experimental approaches, using a colorimeter, and why the initial rate is the one measured.	9
Reading order from concentration-time and rate-concentration graphs	Recall questions on the shapes for each order on both kinds of graph, drawing a tangent, and what a linear gradient gives.	17
The Arrhenius equation and what each symbol means	Recall questions on the exponential and logarithmic forms, what Ea, A, R and T each represent, and why k rises steeply with temperature.	10
The ln k against 1/T plot and finding the activation enthalpy	Recall questions on which quantities are plotted, what the gradient and intercept give, and calculating Ea and A from them.	16
Rate-determining step and mechanism	Recall questions on what the rate-determining step is, what the orders imply about which species take part, and testing a proposed mechanism.	19
Effect of conditions on the magnitude of the equilibrium constant	Recall questions on why only temperature changes Kc, what heating does to an exothermic and an endothermic reaction, and what a catalyst does not do.	20
Economic operating conditions for an industrial process	Recall questions on balancing yield against rate, why very high pressure is not always used, and why a catalyst sets a lower temperature limit.	20
Writing a Kc expression and deducing its units	Recall questions on homogeneous equilibria, writing the expression from a balanced equation, and deducing the units for each case.	11
ICE-table calculations and measuring Kc experimentally	Recall questions on using an initial, change and equilibrium table, converting amounts to concentrations, and measuring Kc for an esterification.	15
Chemical reactions in industrial processes	Recall questions on the stages of nitric and sulfuric acid manufacture, why oleum is made, and the green case for a carbonylation route.	19
Nitrogen, ammonia and the ammonium ion	Recall questions on why nitrogen is unreactive, the shape and bond angle of ammonia and of the ammonium ion, and how the dative bond forms.	11
Oxidation states of nitrogen and the tests for nitrate and ammonium	Recall questions on the oxidation state of nitrogen in its oxides and ions, and the Devarda's alloy and hydroxide tests.	15
Costs, benefits and risks of industrial processes	Recall questions on saleable co-products, the double cost of a by-product, energy recovery, plant capacity and location.	20

The Chemical Industry is 250 of the 3,430 questions in the guide.Get the guide, £8

How the guide is worked

Answering a question from memory stores it far better than reading the answer again. The guide runs that as a fixed procedure on one subtopic at a time, about twenty minutes a session.

Step 1 · Closed book
Cover the answers. Work through one subtopic and write down what you can. Leave blanks where you have nothing.
Step 2 · Open book
Go back to the top. Read each printed answer and write it out in full, including the ones you had right.
Step 3 · Closed book again
Same questions, same order, from memory. The gap between pass one and pass three is the session result.

Read the full method, the return schedule and the research behind it.