All Ion Tests

Question 1

What’s the test for functional group sulfate (SO4)

Answer 1

1. Acidify with dilute HCl
2. Add BaCl2
3. White precipitate

Question 2

What’s the test for functional group carbonate (CO3)

Answer 2

1. Add dilute HCl
2. Effervescence
3. Gas produced turns Limewater cloudy

Question 3

What’s the test for OH-

Answer 3

1. Damp red litmus paper
2. Turns from red to blue

Question 4

What’s the test for the 3 halide ions Cl-, Br-, I-

Answer 4

1. Acidify with dilute HNO3
2. Add AgNO3
3. (Additional test) Add dilute NH3, then conc NH3

Question 5

What’s the test for NH4+

Answer 5

1. Add NaOH
2. Heat
3. Damp red litmus paper turns from red to blue

Question 6

What’s the test for Mg2+

Answer 6

In separate test tubes:
- add dilute NaOH —> white ppt
- add dilute H2SO4 —> no visible change

Question 7

What’s the test for Ca2+

Answer 7

In separate test tubes:
- add dilute NaOH —> white ppt
- add dilute H2SO4 —> slight white ppt

Question 8

What’s the test for Sr2+

Answer 8

In separate test tubes:
- add dilute NaOH —> no visible change
- add dilute H2SO4 —> white ppt

Question 9

Whats the test for Ba2+

Answer 9

In separate test tubes:
- add dilute NaOH —> no visible change
- add dilute H2SO4 —> white ppt

Question 10

What’s the test for 1°, 2°, 3° alcohols

Answer 10

1° & 2°: add acidified potassium dichromate K2Cr2O7 -> orange to green
3° - dichromate remains orange

Question 11

What’s the general test for all alcohols

Answer 11

add metallic Na -> effervescence (H2 gas made)

Question 12

What’s the fehlings test for aldehydes

Answer 12

• warm with fehlings solution
• from blue to red ppt

Question 13

What’s the Tollens test for aldehydes

Answer 13

• warm with tollens reagent
• silver mirror

Question 14

What’s the test for alkenes

Answer 14

• shake with bromine water
• goes from orange to colourless

Question 15

What’s the test for carboxylic acids

Answer 15

Add a carbonate eg Na2CO3
- effervescence
- CO2 released which will turn limewater cloudy

Question 16

How could litmus paper be used to test for pH of oxides

Answer 16

• react with water
• add litmus paper
• if acidic then stays red
• if alkaline then goes from red to blue

Question 17

Why is acidified BaCl2 solution used to test for sulfate ions

Answer 17

The acid reacts with any carbonate ions present. This removes them, so stopping them giving a false positive result

Question 18

What is the equation for AgCl and AgBr dissolving in dilute ammonia?

Answer 18

AgCl + 2NH3 -> [Ag(NH3)2]+ + Cl
AgBr + 2NH3 -> [Ag(NH3)2]+ + Cl

Question 19

How do you test for a Acyl chloride?

Answer 19

• AgNO3 room temp
• steamy white fumes from HCl
• white ppt from AgCl