Question

M2S and Hg2 S are isomorphous with each other and the percentage of S in both the
compounds are respectively 20 and 8% respectively. If atomic Mass Hg is 200.0, atomic mass of
'M' is​

Answer 1

M₂S and Hg₂S are isomorphous with each other and percentage of S in both the compounds are 20% and 8% respectively. atomic mass of Hg is 200 g/mol.

To find : The atomic mass of M.

solution : percentage of S in M₂S = atomic mass of S/molar mass of M₂S × 100

Let atomic mass of M and S are M and x respectively.

⇒20% = x/(2M + x) × 100

⇒1/5 = x/(2M + x)

⇒2M + x = 5x

⇒2M = 4x

⇒M = 2x........(1)

again, percentage mass of S in Hg₂S = atomic mass of Hg/molar mass of Hg₂S) × 100

⇒8% = x/(2 × 200 + x) × 100

⇒2/25 = x/(400 + x)

⇒25x = 800 + 2x

⇒23x = 800

⇒23M = 1600 [ from equation (1), ]

⇒M = 1600/23 = 69.56 g/mol

Therefore the atomic mass of M is 69.56 g/mol