Tests For Ions

Question 1

Mg 2+ (aq)

Answer 1

Add Dil. NaOH, white ppt forms

Mg2+(aq) + 2OH-(aq) –> Mg(OH)2(s)

Question 2

NH4+

Answer 2

Add dil. NaOH, Warm, test gas with red litmus or heat the solid

NH4+(aq) + OH-(aq) –> NH3(g) +H2O(l)
NH3, alkaline gas
NH4+ sublimes to produce a white solid further up the test tube

Question 3

Cl-

Answer 3

1) Acidify with dil. HNO3, Add AgNO3 dropwise to the ppt. Add dil. NH3 followed by conc NH3

White ppt AgCl soluble in Dil NH3

2) Add conc. H2SO4 to solid sample

Steamy Fumes, HCl

Question 4

Br-

Answer 4

Same as Cl-

1) Cream ppt AgBr, soluble in concert NH3
2) steamy fumes HBr, orange fumes Br2

3) add Chlorine water until no change

Solution turns brown

Question 5

I-

Answer 5

Same as Br-

1) yellow ppt of AgI Not soluble in conc NH3
2) steamy fumes HI, black solid I2
3) Solution Turns brown

Question 6

SO42-

Answer 6

Add BaCl2 dropwise followed by HCl sol.,

White ppt forms, BaSO4, Unchanged with HCl

Question 7

CO3 2-

Answer 7

Add acid, test gas by bubbling through limewater,

Colourless solution, effervescence, limewater goes milky

Question 8

HCO3 2-

Answer 8

Heat aqueous solution

Effervescence, limewater goes milky

Question 9

Oxygen

Answer 9

Glowing splint relights

Question 10

Carbon dioxide

Answer 10

Lime water goes milky

Question 11

Ammonia

Answer 11

Red litmus goes blue, with HCl white smoke produced

Question 12

Nitrogen dioxide

Answer 12

This is a brown has, blue litmus turns red

Question 13

Hydrogen

Answer 13

Lit splint produces squeeky pop

Question 14

HCl

Answer 14

Steamy fumes blue litmus goes red, white smoke produced with NH3, white ppt produced when bubbled through AgNO3