Question

What is the mass of one molecule of yellow phosphorus (Atomic mass,P=30)?

Answer 1

>>Yellow phosphorus is an impure form of white phosphorus (P4 ).

>>Molecular mass of yellow phosphorus (P4 ) = ´ = 4 x 30 =120 g/mol

>>According to Avogadros hypothesis,

>>Mass of 6.022 x 1023 molecules of P4 = 120 g

>>and mass of 1 molecule of P4 =120 x 1/ 6.022 x1023 = 19.926 x1023 g

=>>1.993 x10-22g

=>>1 993x10-19mg

Answer 2

Answer: $20.6\times 10^{-23}g$

Explanation: Yellow phosphorus is an impure form of white phosphorus which has atomicity of 4 and is written as $P_4$

Molar mass of yellow phosphorus $P_4=31g\times 4=124g$

According to Avogadro's hypothesis, molar mass contains $6.022\times 10^{23}$ molecule of $P_4$

Mass of $6.022\times 10^{23}$ molecule of $P_4$= 124 g

Mass of 1 molecule of $P_4=\frac{124}{6.022\times 10^{23}}\times 1=20.6\times 10^{-23}g$