Chemical Tests 2h Flashcards

1
Q

Test for hydrogen

A

Lit splint goes out with a squeaky pop

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2
Q

Test for oxygen

A

Glowing splint relights

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3
Q

Test for carbon dioxide

A

Limewater turns milky/cloudy

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4
Q

Test for ammonia (NH3)

A

Damp red litmus turns blue

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5
Q

Test for chlorine

A

Damp blue litmus paper bleaches/turns white

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6
Q

Flame test

A

Clean platinum wire with concentrated HCl
Dip into salt
Hold wire into roaring flame

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7
Q

Flame colour for:
Lithium, Sodium, Potassium, Calcium, Copper (II)

A

Lithium: Red
Sodium: Orange
Potassium: Lilac
Calcium: Red
Copper (II): Green - Blue

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8
Q

Test for ammonium (NH4)

A

Red litmus paper & NaOh

  • Damp red litmus paper turns blue
  • Add warm NaOH and aluminium as catalyst. Strong odour, gas produced (NH3)
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9
Q

Cu (II) with NaOH

A

Blue precipitate formed

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10
Q

Fe (II) with NaOH

A

Green precipitate formed

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11
Q

Fe (III) with NaOH

A

Brown precipitate formed

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12
Q

Tests for halides

A

Add nitric acid to remove impurities
Add silver nitrate to cause precipitation

Chloride: White precipitate
Bromide: Cream precipitate
Iodide: Yellow predipitate

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13
Q

Sulphate test

A

Add hydrochloric acid to remove imputites
Add barium chloride
White precipitate forms if sulphate ion is present

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14
Q

Carbonate test

A

Add any acid
Should bubble
Test bubbles for carbon dioxide

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15
Q

Tests for water

A
  • Anhydrous copper(II) sulphate turns from white to blue
  • Cobalt chloride from blue to pink
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16
Q

Aqueous cation test

A

Aqueous sodium hydroxide is added. The colour of the precipitate is observed to identify the cation.

17
Q

Why does red litmus need to be damp?

A

Water is needed to form hydroxide ions

18
Q

Phenolphthalein colours

A
  • Acid / Neutral: colourless
  • Alkali: pink
19
Q

Methyl orange

A
  • Acid: Red
  • Alkali: Yellow