ESAT Chemical Tests (C16)

Flashcards testing ESAT (Engineering Science Admissions Test) Chemistry chemical tests, chapter C16

Hydrogen

burning splint held at the open end of a test tube, makes a ‘squeaky pop’

Oxygen

relights a glowing splint

Carbon dioxide

limewater turns milky when shaken with gas

Chlorine

damp blue litmus paper turns red and then is bleached (turns white)

Carbonates

dilute acid make carbon dioxide (then limewater)

Halides

silver nitrate make different coloured precipitates (Cl₂ = white, Br₂ = cream, I₂ = yellow)

Chloride ions

first use nitric acid to remove carbonates (white silver carbonate = false positive), then silver nitrate to make white precipitate

Sulfates

first use HCl to remove carbonates, then barium chloride makes insoluble white precipitate

Al³⁺

aqueous sodium hydroxide makes white precipitate

Ca²⁺

aqueous sodium hydroxide makes white precipitate

Mg²⁺

aqueous sodium hydroxide makes white precipitate

Cu²⁺

aqueous sodium hydroxide makes blue precipitate

Fe²⁺

aqueous sodium hydroxide makes green precipitate

Fe³⁺

aqueous sodium hydroxide makes brown precipitate

Li flame test

crimson red

Na flame test

yellow-orange

K flame test

lilac

Ca flame test

red-orange

Cu flame test

green

Water

anhydrous copper(II) sulfate from white to blue