Question

Calculate the no. of molecules of phosphorus (p4). present in 62g of solid phosphorus. ( atoms of
p=31m)​

Answer 1

Answer:

Mole Concept.

Explanation:

P4 = 31 × 4 = 124 Molar mass

Weight = 62 g

★ Quick Trick to get Values out

Mole = No. of molecules / Avagdro number or Weight / Molecular Mass.

So ;

★ No. of molecules / avagadro Number ( Na ) = weight / molecular mass .

No. of molecules = Weight × Na / Mm

= 62 g × 6.023 × 10²³ / 124

= 6.023 × 10²³ / 2

★ No. of molecules = 3 × 10²³ .

[ If no. of atoms would have been asked then multiply the no. of molecules × 4 as solid phosphorus has 4 P atoms . ]

Answer 2

molar mass of P4= 4* 31 => 124 g mol-1

Hence, 1 mol of solid phosphorous has a mass of 124 grams.

As, 1 mol of Phosphorous will have 6.023 X 10^23 molecules of P4.

So 6.023 X 10^23 molecules of P4 have a mass of 124 grams.

Hence, (6.023 X 10^23)/2 molecules of P4 have a mass of 124/2 => 62 grams.

3.0115 X 10^23 molecules of P4 will be present in 62 grams of solid phosphorous.