All Chemical Tests

Question 1

Test for SO4 2- and positive result?

Answer 1

• Acidify with HCl then add BaCl
• White precipitate of BaSO4

Question 2

Test for CO3 2- and positive result?

Answer 2

Add dilute HCl
Effervescence = +ve result

Question 3

Test for OH- and positive result?

Answer 3

Damp red litmus paper
Turns from red to blue

Question 4

Test for Halide ions and positive result for each?

Answer 4

1. Acidify with dilute HNO3
2. Add AgNO3
3. Dilute and concentrated NH3
   Cl- = White ppt,dissolves in dilute NH3
   Br- = Cream ppt dissolves in conc NH3
   I- = Yellow ppt, insoluble

Question 5

Test (‘s) for Mg 2+ ions and positive results?

Answer 5

Dilute NaOH- = White precipitate
Dilute H2SO4= No visible change

Question 6

Test (‘s) for Ca2+ and positive results?

Answer 6

Flame test- Brick red
OH- - White ppt
SO42- - Slight white precipitate

Question 7

Test (‘s) for Sr 2+ and positive results?

Answer 7

Flame test- Red
NaOH- No visible change
H2SO4- Slight white precipitate

Question 8

Test (‘s) for Ba2+ and positive results?

Answer 8

Flame test- Green
NaOH- NO visible change
H2SO4- White precipitate

Question 9

Test for NH4+ and positive result?

Answer 9

Add NaOH
Heat sample
Hold damp red litmus paper at test tube mouth

+ve= litmus paper from red to blue

Question 10

Test for Co 2+ and positive result?

Answer 10

Add NH3 drop wise to excess
Pink to blue solution

Question 11

Tests for Cu 2+ and positive results?

Answer 11

Dilute NaOH- Pale blue ppt
Dilute NH3- Pale blue ppt
Conc NH3- Dark blue solution
Na2CO3- Green-blue solution
NaCl- Yellow solution

Question 12

Tests for Fe 2+ and positive results?

Answer 12

Dilute NaOH- Green precipitate
Dilute NH3- Green precipitate
Na2CO3- Green ppt

Question 13

Test for Fe 3+ and positive results?

Answer 13

Dilute NaOH,dilute NH3 and Na2CO3 - Orange-brown ppt
NaCl- Yellow solution

Question 14

Test for Al3+ and positive result?

Answer 14

Dilute NaOH and Dilute NH3 - WHite ppt
XS NaOH- PPt dissolves
Na2CO3- White ppt an effervescence

Question 15

Test for Alkene and positive result?

Answer 15

Share with bromine water
Solution changes from orange to colourless

Question 16

Test for an alcohol and positive result?

Answer 16

Acidified potassium dichromate
Orange to green for primary and secondary alcohols

Question 17

Tests for an Aldehyde and positive results?

Answer 17

Warm with fehlings solution- Brick red ppt forms from blue solution
Warm with Tollens reagent- Silver mirror

Question 18

Test for a Carboxylic acid and positive result?

Answer 18

Added carbonate
CO2 released (effervescence)