The Chemical Industry

Question 1

Rate of Reaction

Answer 1

The change in the amount of reactants or products per unit time.

Question 2

Measuring Rate of Reaction

Answer 2

· pH (moldm⁻³s⁻¹)
· Gas Volume (cm³s⁻¹)
· Loss of mass (gs⁻¹)
· Colour Change
· Concentration (moldm⁻³s⁻¹)

Question 3

The Rate Equation

Answer 3

A + B → C + D
Rate = k[A]ⁿ[B]ⁱ
n and i are the orders
k is the rate constant

Question 4

Order of Reaction

Answer 4

The Order of a Reaction shows the number of molecules of that reactant are involved in the rate-determining step.
Zero - concentration of reactant changes and the rate is unaffected.
1st - concentration and rate are proportional.
2nd - concentration² and rate are proportional.

Question 5

Half-Life of Different Orders

Answer 5

0 Order - Half life decreases as reaction progresses.
1st Order - Half life is constant. Rate Constant = ln2 / Half Life
2nd Order - Half life increases as reaction progresses.

Question 6

Arrhenius Equation

Answer 6

k = Ae^(-Eₐ/RT)
lnk = -Eₐ/RT + lnA
k - Rate Constant
Eₐ - Activation Energy (Jmol⁻¹)
T - Temperature (K)
R - Gas Constant
A - Pre-Exponential Constant

Question 7

Rate Determining Step

Answer 7

The Slowest Step in a Multi-Step Reaction.
The Reactants involved are in the rate equation.

Question 8

Equilibrium Constant (Kc)

Answer 8

aA + bB → dD + eE
Kc = [D]^d x [E]^e / [A]^a x [B]^b
Kc = [Products] / [Reactants]

Question 9

Effect of Temperature and Pressure on Kc

Answer 9

Pressure has no effect on Kc
Temperature does have an effect of Kc as increasing the temperature causes equilibrium to shift causing the ratio of products to reactants to change.

Question 10

Why is Nitrogen very unreactive?

Answer 10

Nitrogen is naturally a diatomic molecule connected by a triple covalent bond.

Question 11

Ammonia and the Ammonium Ion

Answer 11

Ammonia: NH₃
Ammonium Ion: NH₄⁺
NH₃ + H⁺ ↔ NH₄⁺

Question 12

Nitrous Oxides

Answer 12

NO - Nitrogen Monoxide. Colourless Gas.
N₂O - Nitrous Oxide. Sweet Smell and Colourless Gas.
NO₂ - Nitrogen Dioxide. Brown, Sharp Odour, Toxic.

Question 13

How do you test if an Ammonium Ion is present?

Answer 13

Add Sodium Hydroxide and gently heat. Ammonia Gas is produced turning damp red litmus paper blue.
NH₄⁺ + OH⁻ → NH₃ + H₂O

Question 14

How to test for Nitrate (V) ions

Answer 14

Warm solution and add sodium hydroxide and aluminium. Produced ammonia Gas and turns Red Litmus Blue.
3NO₃⁻ + 8Al + 5OH⁻ + 18H₂O → 3NH₃ + 8[Al(OH)₄]⁻