1.9- Qualitative Analysis

Question 1

Test for carbon dioxide with results

Answer 1

Bubble through limewater ( calcium hydroxide solution )

Limewater changes from colourless to milky
White ppt is soluble and solution wikk turn colourless again in excess

Question 2

Test for hydrogen with results

Answer 2

Put a burning splint over a sample of gas

Burns with a pop

Question 3

Test for oxygen with results

Answer 3

Put a glowing splint into a sample of the gas

Splint relights

Question 4

Test for chlorine with results

Answer 4

Damp universal indicator

Bleaches

Question 5

Test for ammonia with results

Answer 5

1. Damp universal indicator
2. Turns blue
3. Glass rod dipped in conc. HCl
4. Dense white fumes

Question 6

Test for HCL gas with results

Answer 6

1. Damp universal indicator
2. Turns red
3. Glass rod dipped in conc. ammonia solution
4. Dense white fumes

Question 7

What can you deduce from a white crystalline solid

Answer 7

Does not contain transition metal ions
Compound of group 1 2 or ammonium compound

Question 8

What can you deduce from a solid that dissolves to form a colourless solution

Answer 8

Soluble in water
Group 1, 2, aluminium, zinc or ammonium compound

Question 9

What can you deduce from a solid that dissolves to form a coloured solution

Answer 9

Soluble in water
If solution is blue it suggest Cu2+ ions are present

Question 10

What can you deduce from a solid that does not dissolve in water

Answer 10

Not soluble in water

Question 11

How would you carry out a flame test

Answer 11

Dip a nichrome wire/loop into concentrated HCl
Touch sample with the wire
Hold it in a blue Bunsen flame
Record colour observed

Question 12

Lithium flame colour

Answer 12

Crimson

Question 13

Sodium flame colour

Answer 13

Yellow

Question 14

Potassium flame colour

Answer 14

Lilac

Question 15

Calcium flame colour

Answer 15

Brick red

Question 16

Barium flame colour

Answer 16

Green

Question 17

Copper(2) flame colour

Answer 17

Blue-green

Question 18

Describe how you would test for a halide ion

Answer 18

Dissolve a spatula measure of the solid in dilute nitric acid and then add a few cm of silver nitrate SOLUTION
Then add dilute/conc. ammonia SOLUTION

Question 19

Test observations for chloride ions

Answer 19

White ppt which is soluble in ammonia solution to form a colourless solution

Question 20

Test observations for bromide ions

Answer 20

Cream ppt which is soluble in ONLY conc. ammonia to form a colourless solution

Question 21

Test observations for iodide ions

Answer 21

Yellow ppt whip is not soluble in ammonia solution

Question 22

How would you test for sulfate ions and what is observed

Answer 22

Dissolve solid in dilute nitric acid and add a few cm of barium chloride solution

If white ppt formed sulfate ions are present
White ppt is BaSO4

Question 23

How would you test for carbonate ions and what is observed

Answer 23

Place a few cm of dilute acid in a test tube and add the solid

If effervescence is observed and solid disappears carry out the test for CO2

Likewater changed from colourless to milky white

Question 24

How would you test for an ammonium ion and what is observed

Answer 24

Place a few cm of sodium hydroxide SOLUTION in a test tube then warm gently
Test the gas evolved with a glass rod dipped in conc. HCl

Pungent gas evolved, white smoke present with glass rod

Question 25

Test for starch and results

Answer 25

Add a few cm of iodine solution Yellow-brown-> no starch Blue black -> starch present