Question

Calculate the no. of water molecular in a drop 0.0018 ml at room temp (density of h₂0 =1gm/m

Answer 1

• 0.0018ml=0.0018g

Molar mass of H_20

`\\ \sf\longmapsto 2(1u)+16u`

`\\ \sf\longmapsto 16u+2u`

`\\ \sf\longmapsto 18g/mol`

Now

`\boxed{\sf No\;of\:moles=(Given\:Mass)/(Molar\:Mass)}`

`\\ \sf\longmapsto No\:of\;moles=(0.0018)/(18)=0.0001mol`

Now

`\boxed{\sf No\;of\;molecules=No\:of\;moles* Avagadro\:No}`

`\\ \sf\longmapsto 0.0001* 6.023* 10^(23)`

`\\ \sf\longmapsto 0.0000166* 10^(23)`

`\\ \sf\longmapsto 1.6* 10^(18)molecules`