Chemistry Practical notes

Things I need to know for the Chemistry Assessed Practicals, AS level. 

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  • Created by: Tom
  • Created on: 11-03-12 18:04

Colour of solid salts (8)

Blue - Copper (II)

Pale green - Iron (II)

Green - Copper (II), Nickel (III), Chromium (III)

Purple - Manganate (VII)

Brown - Iron (III)

Pink - Manganese (II)

Yellow - Chromate (VI)

Orange - Dichromate (VI)

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Flame Tests

Yellow Sodium

Lilac Potassium

Yellow-red Calcium

Red Lithium, Strontium

Pale Green Barium

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Recognition & Identification of common gases

Oxygen - Colourless gas which relights a glowing splint

CO2 - Colourless gas which gives a white precipitate with limewater (calcium hydroxide solution)

Ammonia - Colourless gas which turns moist red litmus paper blue and forms white smoke with hydrogen chloride

NO2 - Brown gas, insoluble in organic solvents

Hydrogen - Colourless gas which ignites with a pop

Hydrogen chloride - Steamy fumes on exposure to moist air, acidic and forms white smoke with ammonia

Chlorine - Pale green gas which bleaches moist litmus paper

Bromine - Brown gas, soluble in organic solvents to form a brown solution

Iodine - Purple vapour

Water vapour - Turns blue cobalt chloride paper pink

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Action of dilute acids

Action of acid Possible source

CO2 evolved Carbonate

Hydrogen evolved A metal

Yellow solution turns orange Chromate (VI) to dichromate (VI)

SO2 evolved and pale yellow Thiosulfate

precipitate formed

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Sodium hydroxide solution

Observation on adding dilute NaOH   Excess NaOH soluble? Likely Ion

Green ppt turns brown when exposed to air   Insoluble Iron (II)

Brown ppt    Insoluble Iron (III)

Blue ppt    Insoluble Copper(II)

White ppt    Dissolves to colourless aq Zinc (II)

White ppt    Insoluble Mg, Ba, Sr, Ca

No ppt but ammonia evolved on warming        Ammonium

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Silver Nitrate Solution

Anion - Ppt colour -  Addition of aqueous NH3 (Dilute/Concentrated)

Chloride - White -  Soluble

Bromide   - CreamSoluble in excess/soluble

Iodide - Yellow -  Insoluble/insoluble

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Concentrated Sulphuric Acid

Halide - Observations on adding conc. H2SO4 - Observed Reaction products

Chloride   Steamy fumes, vig. reaction    HCl

Bromide   Steamy fumes, brown vapour, vig. reaction.    HBr, Br2, (SO2)

Iodide   Steamy fumes, black solid, purple vapour, yellow solid, vig. reaction HI, I2, S, (H2S)

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