Compilation

Ag

Ag

Ag +

Cu

Cu 2+

Pb

Pb 2+

Zn

Zn 2+

H

H +

OH

OH -

NH4

NH4 +

CO₃

CO₃ 2-

NO3

NO3 -

SO4

SO4 2-

Why do covalent compounds not conduct electricity?

They have no ions or electrons free to flow and carry charge

What is the positive electrode called?

Anode

What is the negative electrode called?

Cathode

In electrolysis of a solution, if the cation metal is more reactive than hydrogen, what is produced?

Hydrogen

In electrolysis of a solution, if the cation metal is less reactive than hydrogen, what is produced?

The metal (ONLY Cu, Ag, Au, Pt)

In electrolysis of a solution, if the negative ion is a halide, what is discharged?

Halide ions are discharged; a halogen is formed. OH- ions stay in solution.

In electrolysis of a solution, if the negative ion is a sulphate, carbonate or nitrate, what is discharged?

OH- ions are discharged and oxygen is formed. SO₄, CO3_, and NO₃ ions stay in solution.

4OH^- —> 2H₂O + O₂ + 4e^-

In electrolysis of dilute H₂SO₄, twice as much hydrogen forms as oxygen. Why is this?

For every 4 electrons that flow around the circuit:

• 2 moles of H₂ and

• 1 mole of O₂ are produced.

Negative Electrode (cathode):

• 2H⁺ + 2e^- —> H₂

Positive Electrode (anode):

• 4OH^- —> 2H₂O + O₂ + 4e^-

Where are metals extracted from?

Most are extracted from ores found in the Earth’s crust however a few unreactive metals like gold are found native.

How are metals less reactive than carbon extracted from their ores?

Reduction using carbon.

The ore is heated with carbon, which serves as the reducing agent.

How are metals more reactive than carbon extracted from their ores?

Electrolysis

What four metals occur native and do not need to be extracted?

Cu, Ag, Au, Pt

Define metallic bonding

The electrostatic force of attraction between the positive metal ions and the delocalised electrons

Give percentages in the atmosphere of gases:

• Nitrogen

• Oxygen

• Argon

• Carbon dioxide

• 78% Nitrogen

• 21% Oxygen

• 0.9% Argon

• 0.04% Carbon Dioxide

What is an alloy?

A mixture of a metal and one or more elements (usually other metals or carbon)

Define functional group.

A group of atoms responsible for the characteristic reactions of a particular compound

Give 5 similarities of a homologous series.

• Same general formula

• Same functional group

• Similar chemical properties

• Trends in physical properties

  • Differ by -CH₂ units

Describe fractional distillation of crude oil

• Heated crude oil is fed into a fractionating column

• The column is hot at the bottom and cool at the top

• Hydrocarbons with very high boiling points condense at lower heights, those with low boiling points rise up at the column and condense higher up.

  • The different fractions condense at different heights according to their boiling points

Why can nitrogen oxides be formed in car engines?

The temperature reached is high enough for nitrogen and oxygen in the air to react

Name three ways of oxidising ethanol

• Burning in air or oxygen (complete combustion)

• Reacting with oxygen in air to form ethanoic acid (microbial oxidation)

• Heating with potassium dichromate(VI) in dilute sulfuric acid to form ethanoic acid

Describe how to oxidise ethanol with potassium dichromate (VI) and dilute sulphuric acid.

• Add a few drops of ethanol to a test tube with the orange mixture of [oxidising agent] potassium dichromate(VI) and dilute sulphuric acid.

• Heat the test tube under in a water bath

• The solution turns from orange to green as the alcohol is oxidised to the carboxylic acid

State the chemical equation for oxidising ethanol with potassium dichromate (VI) and dilute sulphuric acid.

CH₃CH₂OH + 2[O] —> CH₃COOH + H₂O

Give the chemical equation for fermentation

C₆H₁₂O₆ (aq) -yeast-> 2C₂H₅OH (aq) + 2CO₂ (g)

Give the chemical equation for the hydration reaction (ethene + steam)

C₂H₄ (g) + H₂O (g) —> C₂H₅OH (g)

What are the conditions for the hydration reaction?

• Starting material: ethene and steam

• Pressure: 60-70 atmospheres

• Temperature: 300 ^oC

• Catalyst: phosphoric acid

What are the conditions for fermentation?

• Starting material: Glucose from sugar cane

• Pressure: 1 atmosphere

• Temperature: 30 ^oC (no higher than 40 ^oC so yeast enzymes don’t denature)

• Catalyst: enzymes in yeast

• Special conditions: anaerobic

What is special about vinegar?

It is an aqueous solution containing ethanoic acid

Describe how to make an ester.

• Heat a mixture of a carboxylic acid and an alcohol with a few drops of concentrated sulphuric acid catalyst

• Reaction type: ESTERIFICATION

alcohol + carboxylic acid —> ester + water

What are the products of condensation polymerisation?

Polyester and water

diol + dicarboxylic acid —> polyester + water