Chemistry IGCSE

Order of fractions in refining petroleum (top to bottom):

• refinery gas

• gasoline

• naphtha

• kerosene

• diesel oil

• fuel oil

• lubricating fraction

• bitumen

Refinery gas use:

bottled gas for heating and cooking

Gasoline uses:

petrol for cars

Naphtha uses:

making chemicals and plastics

Kerosene uses:

fuel for aeroplanes, oil stoves and oil lamps

Diesel oil uses:

fuel for diesel engines

Fuel oil uses:

power stations, ships, home heating systems

Lubricating fraction uses:

lubricants for car engines, machinery, waxes and polishes

Bitumen uses:

making roads, covering roofs

Cracking alkanes:

breaks non-useful long chain alkanes to smaller alkanes and at least one alkene

Cracking alkanes process:

• vaporised alkanes are passed over a catalyst

• requires 600-700°C

• requires silica or alumina/zeolite catalysts

Identification of alkenes:

bromine water goes from orange to colourless thanks to an addition reaction

Hydrogenation reactions:

• alkene + hydrogen —> alkane

• requires a nickel catalyst

• requires 150°C

Hydration reaction:

• alkene + steam —> alcohol

• requires 300°C

• requires 60-70 atm of pressure

• requires a phosphoric acid catalyst

Combustion of alkanes:

alkane + oxygen —> carbon dioxide + water (+ heat)

Substitution reaction between alkanes and chlorine:

• alkane + chlorine gas —> hydrogen chloride + chloroalkanes

• requires UV light (photochemical reaction)

Polymerisation of alkenes requires:

• heat

• pressure

• catalyst

Anhydrous copper (II) sulfate colour:

white

Hydrated copper (II) sulfate colour:

blue

Anhydrous cobalt (II) chloride colour:

blue

Hydrated cobalt (II) chloride colour:

pink

Source of nitrogen for the Haber process:

air

Haber process:

process to make fixed nitrogen

Source of hydrogen for Haber process:

methane

Typical conditions of the Haber process:

450°C, 200 atm, iron catalyst

Contact process:

process to produce sulfuric acid

Source of sulfur dioxide in Contact process:

burning sulfur, roasting sulfide ores

Source of oxygen for Contact process:

air

Typical conditions for the conversion of sulfur dioxide to trioxide in the Contact process:

450°C, 2 atm, vanadium oxide catalyst

Acidified KMnO4 colour changes

purple to colourless when mixed with a reducing agent

Aqueous Potassium iodide colour changes:

colourless to reddish-brown when mixed with an oxidising agent

Catalytic converter catalyst

platinum and rhodium

Avogadro constant (number of particles per mol)

6.02×10²³

Electrolysis of molten lead(II) bromide

anode: bromine (brown gas)

cathode: lead (dark grey metal coat)

Electrolysis of concentrated aq. sodium chloride (brine)

anode: chlorine (green bubbles)

cathode: hydrogen bubbles

Electrolysis of dilute sulfuric acid:

anode: oxygen bubbles

cathode: hydrogen bubbles

Electrolysis of aq copper (II) sulfate with non-copper electrodes:

anode: oxygen bubbles

cathode: copper (red-brown metal coating)

Electrolysis of aq copper (II) sulfate with copper electrode:

anode: oxygen bubbles + electrode shrinks

cathode: electrode gets bigger

Solubility of sodium salts:

all soluble

Solubility of potassium salts:

all soluble

Solubility of ammonium salts:

all soluble

Solubility of nitrate salts:

all soluble

Solubility of chloride salts:

all soluble except lead and silver

Solubility of sulfate salts:

all soluble except barium, calcium and lead

Solubility of carbonate salts:

all insoluble except potassium, ammonium and sodium

Solubility of hydroxide salts

all insoluble except sodium, ammonium, potassium, and calcium (partially)

CO3 2- test

Add dilute acid, CO2 bubbles

Cl- test

Acidify with nitric acid, add silver nitrate. White precipitate formed (AgCl)

I- test

Acidify with nitric acid, add silver nitrate. Yellow precipitate formed (AgI)

Br- test

Acidify with nitric acid, add silver nitrate. Cream precipitate formed (AgBr)

NO3- test

Add NaOH, add aluminium gently. Ammonia formed.

SO4 2- test

Acidify, add barium nitrate. White precipitate (Barium Sulfate) forms

SO3 2- test

Add dilute HCl, warm gently. SO2 produced.

Al 3+ and aq NaOH

White precipitate. Clear solution. Soluble in excess.

Al 3+ and aq NH3

White precipitate. Insoluble in excess.

NH4 + and aq NaOH

Red brown precipitate, insoluble in excess

Ca 2+ and aq. NaOH

White precipitate. Insoluble in excess

Ca 2+ and aq. NH3

Nothing

Cr 3+ and aq NaOH

Greenish precipitate, insoluble in excess.

Cr 3+ and aq NH3

Greenish precipitate, insoluble in excess

Cu 2+ and aq NaOH

Blue precipitate, insoluble in excess

Cu 2+ and aq. NH3

Turquoise precipitate, dark blue solution in excess.

Fe 2+ and aq. NaOH

Green precipitate in clear solution, insoluble in excess.

Fe 2+ and aq. NH3

Greenish precipitate, insoluble in excess.

Fe 3+ and aq. NaOH

Orange-brown precipitate, insoluble in excess

Fe 3+ and aq. NH3

Orange-brown precipitate, insoluble in excess.

Zn 2+ and aq. NaOH.

White precipitate, clear colourless solution, soluble in excess,

Zn 2+ and aq. NH3

White precipitate, colourless solution in excess

Ammonia test

Turns damp red litmus paper on top of container blue

CO2 test

Limewater turns milky

H2 test

Lit splint, squeaky pop

O2 test

Glowing splint relights

SO2 test

Turns acidified KMnO4 from purple to colourless

Cl2 test

Bleaches damp litmus paper

Li+ flame test

red

Na+ flame test

yellow

K+ flame test

lilac

Ca 2+ flame test

red

Ba 2+ flame test

green

Cu 2+ flame test

blue-green

Graphite structure

• Allotrope of carbon

• Each carbon atoms forms covalent bonds with 3 others, forming hexagons of strong bonds

• The atoms each lose the fourth electron, which stays between layers and holds the layers together with weak electrostatic forces

Diamond structure

• Allotrope of carbon

• Each carbon atom forms 4 covalent bonds with 4 other atoms

• Forms a tetrahedron

Silicon (IV) dioxide structure

• Each silicon atom forms covalent bonds with 4 oxygen atoms, and each oxygen atom forms covalent bonds with 2 silicon atom

• forms tetrahedron structure

Flue gas desulfurisation

reacting sulfur dioxide in flue gas with calcium oxide to remove sulfur

Relative mass of an electron

1/2000

Top number in an atomic symbol

Mass number

Bottom number in an atomic symbol

Proton number

Properties of ionic compounds:

• high melting and boiling point (strong intermolecular forces between oppositely charged ions)

• conduct electricity when molten/aqueous

Properties of covalent bonds:

• strong intramolecular forces

• weak intermolecular forces

• low boiling and melting point

• electrical insulator

How do enzymes work?

provide a pathway that needs less activation energy

Formula of hydrated copper sulfate:

CuSO4.5H2O

Formula of hydrated cobalt chloride:

CoCl2.6H2O

Flame colour vs alkane chain length:

Short chain: blue flame, little smoke

Long chain: yellow smoky flame