GCSE Chemistry Paper 2 missed questions

How do you ensure all water evaporates from a evaporating basin?

heat until constant mass

What is 1cm³ in dm³?

0.001dm³

Which changes of state take place during fractional distillation and where?

• Evaporation in heater

• Condensation in fractionating column

How does an oxide coating protect a aluminium from corrosion?

It acts as a barrier, preventing oxygen reaching the metal.

How did the percentage of nitrogen change in Earth’s early atmosphere?

Nitrogen increased due to intense volcanic activity

What are the two reasons for carbon dioxide decreasing in Earth’s early atmosphere? (4.5-3 bill yrs ago)

1. Carbon dioxide dissolved into water/oceans

2. Carbonate formed sediments/precipitates

Which 7 elements are diatonic? (Have no fear of ice cold beer)

Have - hydrogen

No - nitrogen

Fear - flourine

Of - oxygen

Ice - iodine

Cold - chlorine

Beer - bromine

Why does a solution of a stronger acid react more vigorously than a weak one?

A stronger acid solution has a higher concentration of hydrogen ions, increasing frequency of collisions

What is the main condensation polymer, produced by a diol and dicarboxylic acid?

Polyester

What do amino acids polymerise into?

Polypeptides

What are the two functional groups of an amino acid?

-NH2 and -COOH

Describe the structure of a thermosetting polymer

Long chain molecules with covalent bonds between the chains

Describe the structure of a thermoforming polymer

Long chain molecules, tangled together with weak inermolecular forces between chains

How do catalysts increase rate of reaction?

Provide a different reaction pathway, lowering activation energy, increasing rate of reaction

How does increasing temperature increase rate of reaction?

Particles have more kinetic energy so move faster and collide more frequently

What does using a high pressure do in a reversible reaction?

Shifts the position of equilibrium to the side with less moles

What are the percentages of the two main gasses in the atmosphere?

78% nitrogen

21% oxygen

How is ammonia seperated from the reaction of nitrogen and hydrogen?

The mixture is cooled so ammonia condenses but nitrogen and hydrogen remain gases.

What is the test for alkenes?

Reacts when shaken with bromine water, turning the solutionm orange-brown to colourless

What is the name of the alcohol functional group?

Hydroxyl group (-OH)

How is acid rain caused? [3]

Sulfur impurities in fossil fuels oxidise when burned into sulfur dioxide, dissolving in rainwater to form sulfuric acid