Qualitative Tests

Question 1

How do you test for CO2?

Answer 1

Pass thru limewater

Question 2

What is a pos result for CO2?

Answer 2

Colourless to milky

Question 3

What indicates CO2 in XS?

Answer 3

Milky white ppt is sol and forms colourless solution

Question 4

How do you test for H2? and Positive Result:

Answer 4

Burning splint into a sample of gas
Burns with a pop

Question 5

How do you test for 02?

Answer 5

Put glowing splint into the sample of gas
Splint relights

Question 6

How do you test for Cl2?

Answer 6

Damp litmus/ universal ind paper
Bleaches

Question 7

How do you test for NH3?

Answer 7

Damp universal ind paper, then glass rod dipped in conc HCl acid.
Pos: turns blue and dense white flame

Question 8

How do you test for HCl?

Answer 8

Damp universal indicator, glass rod dipped in conc NH3 sol
Pos: Turns reed and dense white flames

Question 9

How do you dissolve a sol in h20?

Answer 9

Add a few spatula measures to a tt of deionised water and shake to mix
If it dissolves to form a col sol- Gr1/2/ammonium ion/ Zn/Al compound

Question 10

How do you carry out a flame test?

Answer 10

Dip nichrome wire loop in conc Hcl acid, touch sample with wire, then hold it in Blue Bunsen flame

Question 11

What is the colour of Li+?

Answer 11

Crimson

Question 12

Na+

Answer 12

Yellow/orange

Question 13

K+

Answer 13

Lilac

Question 14

Ca2+

Answer 14

Brick Red

Question 15

Ba2+

Answer 15

Green

Question 16

Cu2+

Answer 16

Blue-Green

Question 17

How do you test for the presence of halide ions?

Answer 17

Dissolve a spatula measure of solid sample in dilute HNO3 and add a few cm3 AgNO3 sol
Add dilute/ conc NH3 sol

Question 18

What are the obs if Cl- present?

Answer 18

White ppt (AgCl) sol in both dilute and conc NH3 sol-> col. sol

Question 19

What are the obs if Br- present?

Answer 19

Cream ppt (AgBr) - not sol. in dilute NH3 but sol in conc NH3 sol -> col. sol.

Question 20

What are the obs if I- present?

Answer 20

Yellow ppt not sol. in either dilute/ conc NH3 sol.

Question 21

How do you test for SO2-4 ions?

Answer 21

Dissolve spatula measure of s sample in dilute HNO3 acid (HCl acid also works) and add a few cm3 BaCl2
White ppt ( BaSO4) means present

Question 22

How do you test for Carbonate Ions?

Answer 22

Place a few cm3 dilute acid in t.t and add a spatula measure of solid sample

Question 23

What are the obs if CO2-3 ions are present?

Answer 23

Effervescence
S disappears
Gas evolved can be passed thru limewater in another t.t using a delivery tube
Limewater: colourless -> milky

Question 24

How do you test for NH+4?

Answer 24

Place a few cm3 NaOH sol in tt and add spatula measure of a sample- warm gently
Test any gas evolved using damp red litmus paper/ glass rod dipped in conc HCl acid

Question 25

What are the obs if NH+4 present?

Answer 25

Pungent gas
Damp ind changes to blue
White smoke with glass rod dipped in conc HCl acid

Question 26

How do you test for starch sol?

Answer 26

Add a few cm3 starch sol to a sample

Question 27

What happens if starch present/ not present?

Answer 27

Present: Blue-Black
Not Present: No blue-black- remains yellow-brown