Unit 7 - Analysis Flashcards Preview

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Flashcards in Unit 7 - Analysis Deck (24)
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1
Q

Test for ammonia

A
  • it has a pungent smell
  • turns damp red litmus paper blue
  • with the stopper of concentrated HCl it gives a white smoke (ammonium chloride)
2
Q

Test for Cu++ (copper)

A

Dissolve compound in water and add dilute sodium hydroxide.
If test is positive, a pale blue precipitate will be formed.
Cu++ + 2OH- –> Cu(OH)2

3
Q

Test for Fe++ (iron II) ions

A

Dissolve compound in water and add dilute sodium hydroxide.
If test is positive, a moss green precipitate will be formed.
Fe++ + 2OH- –> Fe(OH)2

4
Q

What happens when you dissolve potassium, sodium, or ammonium ions in sodium hydroxide

A

There is no precipitate as these hydroxides are soluble in water

5
Q

Test for Cl- (chloride) ions

A

Dissolve the compound in water. Add aqueous silver nitrate and dilute aqueous nitric acid. If test is positive a white precipitate will form.
Ag+ + Cl- –> AgCl

6
Q

How to perform a flame test

A

Use a clean platinum wire
Dip it in concentrated hydrochloric acid
Dip it in powdered compound
View the colour of the flame

7
Q

Ion gives a brick red flame in a flame test

A

Ca++ (calcium)

8
Q

What colour gives an intense yellow flame in a flame test

A

Na+ (sodium)

9
Q

What ion gives a green (blue centre) flame in a flame test

A

Cu++ (copper)

10
Q

What ion gives a lilac flame in a flame test

A

K+ (potassium)

11
Q

What ion gives a bright red flame in a flame test

A

Li+ (lithium)

12
Q

Test for ion Br- (bromide)

A

Dissolve the compound in water. Add aqueous silver nitrate and dilute aqueous nitric acid. If test is positive a cream precipitate will form (silver bromide)

13
Q

Test for I- (iodide) ions

A

Dissolve the compound in water. Add aqueous silver nitrate and dilute aqueous nitric acid. If test is positive a primrose yellow precipitate will be formed (silver iodide)

14
Q

Test for the anion SO4 – (sulfate)

A

Dissolve the compound in water and add aqueous barium chloride solution (and HCl to remove carbonates). BaSO4 is insoluble in water so a white precipitate will form.

15
Q

Test for anion CO3 – (carbonate)

A

Add dilute HCl. If there is effervescence it is either CO2 or H2. If the gas is CO2 then a carbonate is present
CO3 – + 2H+ –> CO2 + H2O

16
Q

Test for hydrogen

A

Lit splint in gas gives a squeaky pop

17
Q

Hazards of hydrogen

A

It’s highly flammable (could explode)

18
Q

Test for oxygen

A

Glowing splint relights in gas

19
Q

Hazards of ammonia

A

It’s poisonous

20
Q

Test for carbon dioxide

A

Bubble gas through limewater, it goes milky (goes clear again after a while)

21
Q

Test for chlorine gas

A

Damp litmus paper is bleached white

22
Q

Hazards of chlorine

A

It’s highly poisonous

23
Q

Test for water vapour

A

Anhydrous copper sulfate turns from white to blue

24
Q

Test for NH4+ (ammonium)

A

Dissolve the compound in an alkali (sodium hydroxide) and heat it. On heating, ammonia is less soluble, so it is released.
NH4+ (s) + OH- (aq) –> NH3 (g) + H2O (g)