Question

Calculate the number of molecules in 8 g of O2 and number of moles in 52 g of He.[Atomic mass of O-16 u; He-4 u]

Answer 1

Moles= given mass/molar mass.................
Molar mass of O2=32u, given mass=8g.molar mass of He=4u, given mass= 52g




Mole(O2)= 8/32=1/4 moles or 0.25 moles

Molecules= (1/4)* 6.022*10^23= 1.5055*10^23 molecules


Moles(He)= 52/4=13/2(molecule of He)=6.5 moles

Molecules= (65/10)* 6.022*10^23
= 391.43*10^22 molecules

Answer 2

Answer:

No of molecules in 8g of O2 is 1.555×10²³

No of moles in 52g of helium is 13

Explanation:

No of molecules=given mass/molar. mass×Avogadro number

= 8/32×6.022×10²³

=1.555×10²³

No of moles= given mass/molar mass

= 52/4

=13