Question

3. Convert into mole:
a) 12g of oxygen gas
b) 20 g of water​

Answer 1

Answer:

mole=given mass/molar mass

molar mass of oxygen =16

but here is oxygen gas meansO2=16×2=32

given mass =12

A's above formula

mole=12/32=6/16=3/8

Answer 2

Given:-

→Mass of oxygen gas(O₂)=12g

→Mass of water(H₂O)=20g

To find:-

•Number of mole in 12g oxygen gas

•Number of mole in 20g water

Solution:-

For 12g oxygen gas:-

•Atomic mass of Oxygen=16u

Thus,molecular mass of Oxygen gas i.e. O₂:-

=>16×2

=>32u

Since,molecular mass of O₂ is 32u,thus it's molar mass is 32g.

Now,number of moles:-

=>Given Mass/Molar mass

=>12/32

=>0.375 mole

For 20g water:-

Water has two elements,Hydrogen and Oxygen.

•Atomic mass of Hydrogen=1u

•Atomic mass of Oxygen=16u

Thus,molecular mass of water i.e. H₂O is :-

=>1×2+16

=>18u

Since,molecular mass of H₂O is 18u,thus it's molar mass is 18g.

Now,number of moles:-

=>Given Mass/Molar mass

=>20/18

=>1.11 mole