Question

. a) Define atomic mass unit.
b) Write the chemical formula of sodium sulphite
c) Calculate the number of moles of phosphorus (P4) present in 16g of solid phosphorus​

Answer 1

a unit of mass used to express atomic and molecular weights, equal to one twelfth of the mass of an atom of carbon-12.

Sodium sulfide is the chemical compound with the formula Na2S, or more commonly its hydrate Na2S·9H2O.

3. No. of moles = Given Mass / molar mass

No. of moles = 16 g / 31 x 4 g = 16 / 124

No. of moles = 2 moles

No. of particles = No. of moles * Avogadros' constant

No. of particles = 2 moles * 6.022 * 1023 = 12.044 * 1023