qualitative analysis

Question 1

qualitative analysis;

Answer 1

involves finding out the chemical nature of unknown substances.

Question 2

gas tests- Oxygen

Answer 2

test; with a glowing splint

observe: splint relights

Question 3

GT- Hydrogen

Answer 3

test; with lighted splint or naked flame

observe- squeeky pop

Question 4

GT- co2

Answer 4

test- bubble through limewater

observe- limewater turns milky

Question 5

GT- Ammonia

Answer 5

test- damp red litmus paper

observe- turns blue

Question 6

GT- Chlorine

Answer 6

test 1- damp blue litmus paper
observe- turns it red, then bleaches it white

test 2- bubble through aq KBr solution
observe- Kbr solution turns brown as Br2 displaced from solution

Question 7

water

testing for metal ions- group 1 compounds

Answer 7

are soluble and give colourless solutions

Question 8

water

TMI- group 2 compounds

Answer 8

are often soluble and give colourless solutions

Question 9

water

TMI- Transition metals compounds

Answer 9

give coloured solutions

Question 10

flame tests process

Answer 10

1) a nichrome wire is placed in concentrated HCL solution, and then heated in the hottest part of a blue flame to clean it.
2) a small sample of the compound or its aq solution is then placed onto the wire and returned to flame.
3) different compounds give different coloured flames

Question 11

testing for other ions:

ammonium NH4

Answer 11

test :
heat compound with NaOH solution
-the gas released is tested with damp red litmus paper

observe:
paper turns blue due to the formation of ammonia gas

Question 12

testing for C03, 2-

Answer 12

test
add dilute HCL and test gas evolved with limewater

observe:
limewater turns milky

Question 13

testing for Chloride

Answer 13

test
add dilute nitric acid then silver nitrate solution (AgNO3) test ppte with dilute aq ammonia

observe;
white ppte forms
dissolves in dilute aq ammonia

Question 14

testing for bromide ions

Answer 14

test
add dilute nitric acid then silver nitrate solution
test ppte formed with dilute aq ammonia

observe:
cream ppte forms.
ppte is insoluble in dilute ammonia solution but dissolves in concentrated ammonia solution

Question 15

test for iodide ions

Answer 15

test
same as br

observe:
yellow ppte forms
is insoluble in dilute + concentrated aq ammonia solution