CHEM IGCSE 🚨🚨🚨

Test for hydrogen

Lit splint creates squeaky pop

Test for oxygen

Glowing splinter relights

Test for Carbon dioxide

Bubbled through limewater, turns milky/cloudy

Test for chlorine

Damp litmus is bleached

Test for ammonia

Glass rod dipped in hydrochloric acid, put this in test tube

White smoke of ammonium chloride is observed

Flame test - lithium

Red

Sodium flame test

Yellow

Potassium flame test

Lilac

Calcium flame test

Orange -red

Copper flame test

Blue-green

Identify a strongly acidic substance

Hydrochloric acid

Identify and weakly acidic substance

Ethanoic acid

Identify a neutral solution

Water, sodium chloride

Identify a Weakly alkaline solution

Ammonia

Identify a strongly alkaline solution

Sodium hydroxide

Litmus is

Red in acids, blue in alkalis

Methyl orange

Red in acids, yellow in alkalis

Phenolphthalein Is

Colourless in acids, pink in alkalis

Universal indicator is

Red in acids, blue in alkalis

Metal + acid —>

Salt + hydrogen

Metal carbonate + acid —>

Salt + water +carbon dioxide

Metal oxide/hydroxide + acid —>

Salt + water

Test for halide anions

Dilute nitric acid , them silver nitrate

Chloride

White precipitate —silver chloride

Bromide , Br-

Cream precipitate— silver bromidde

Iodide, I-

Yellow precipitate — silver iodide

Test for ammonium

Add sodium hydroxide and warm mixture

Test for gas with DAMP RED LITMUS PAPER TURNS BLUE

Test for sulfates

Add hydrochloric acid

Add barium chloride —> white precipitate is formed

Test for carbonates

Add dilute hydrochloric acid —> fizzing (effervescence) occurs

Test fo r presence of water

Anhydrous copper sulfate turns blue

Calcium cation test

White precipitate

Iron (II), cation test Fe2+

Green ppt

Iron (III) cation test fe3+

Brown

Aluminum cation test Al3+

Colourless

Exothermic

Reactants are losing heat

Appears hotter

Endothermic reactions

Absorb heat from the surroundings

How to calculate heat change

Q = mc∆t

Bond breaking…

…needs energy -endothermic

Bond making…

…releases energy — exothermic

The specific heat capacity of water

4.18/J/g/°c

Hydrocarbons

Molecules that contain carbon and hydrogen only

Saturated compunds

Compounds that only single C-C bonds

Unsaturated compounds

Containing double or triple C-C bonds

Reactions of alkanes with alkane sin the presence of UV

Halogen + alkane —> halogenoalkane + hydrogen halide

Why not sulfuric acid for carbonate test

Will form insoluble layer of calcium sulfate around calcium carbonate, which stops the reaction

Simple distillation

Obtains water by evaporating and condensing vapours

Separates a solvent from solution or mixture of two liquids

Fractional distillation

Separate two or more liquids with different boiling points

Filtration

Separated an insoluble solid from liquid

Solvent

A substance that dissolves in another substance

Solute

A substance that dissolves in a solvent

Solution

Solute dissolved in solvent

Saturated solution

A solution that can take no more solute at a given temperature

Crystallisation

Producing crystals by evaporating solvent

Chromatography

Separated different colour soluble substances

Can be used to distinguish impure substances

Rf value

(Distance traveled by substance) / (Distance traveled by solvent) 

Atom

A particle with a nucleus ans no overall charge

Molecule

A particle made up of two or more atoms held together by covalent bonds, no overall charge

Sacrificial metals

When a more reactive metal is attched to a less reactive metal the more reactive metal will oxidise and corrode first, protecting iron underneath

Catalyst

Provide an alternative pathway with a lower activation energy

Homologous series

Series of compounds with the same general formula and similar properties

Functional group

A group of atoms responsible for the chemical reactions of a compound