GROUP 5 + 6

Question 1

The elements of group V react with

Answer 1

water and dil. acids

to form divalent ions and H2 gas

Question 2

Ba, Sr, and Ca (not Mg) rapidly oxidized in moist air, forming a mixture of oxides and hydroxides.

Answer 2

Therefore, these elements must be stored in sealed containers or be covered with mineral oil or kerosene

Question 3

flame test

Calcium

Answer 3

Brick-red

Question 4

flame test

Strontium

Answer 4

Crimson

Question 5

flame test

Barium

Answer 5

Yellowish green

Question 6

group 5 with NH4OH (ex)

Answer 6

Turn the medium basic ammoniacal.

Question 7

group 5 with NH4Cl

Answer 7

to reduce the ionization of NH4OH by common ion effect.

Question 8

group 5 with (NH4)2HPO4 (ammonium monohydrogen phosphate)

Answer 8

Precipitate the cations

Question 9

Confirmatory test for Ba2

K2CrO4 +BaSO4
When potassium chromate is added to Ba2+solution

Answer 9

BaCrO4
Yellow ppt

Question 10

Confirmatory test of Ca2+

Ca2+ + C2O4 2-
Precipitate Ca as Calcium oxalate monohydrate

Answer 10

CaC2O4 .H2O
white ppt

Question 11

Confirmatory test of Mg2+

By making the solution basic with NaOH
Mg2+ + NaOH →

Answer 11

A white ppt. of Mg(OH)2

Question 12

Na+ and K+ can be detected by

Answer 12

Flame test

Question 13

Na+ →

Answer 13

Golden-yellow colour

Question 14

K +

Answer 14

Violet colour

Question 15

Ammonium salts are detected by

Answer 15

heating the sample with NaOH

can be detected by its odour, or by Conc. HCl on glass rod
white fumes o