Question

Calculate the number of molecules present in
a) 0.9 g of water b) 1.7 g of ammonia​

Answer 1

Calculate he number of moles you have by taking the Mass / molar mass. if you have 1000 grams ; then 1,000 g / 151.001 g/mol = X g moles. Then multiply by Avogadros # = 6.022140857 × 10^23 molecules per g mole. The result is the # of molecules of MnSO4.

Answer 2

Answer:

moles of water =

18

0.9

= 0.05

no. of water molecules = 0.05 x6.02 x10

23

= 3.010 x 10

22

1 water molecule contains 1 oxygen atom

mo. of oxygen atoms = 3.010 x 10

22

1.7 gram of ammonia (molecular weight 17 g/mol) =

17 g/mol

1.7 g

=0.1 mol.

The number of molecules in 1.7 gram of ammonia =0.1 mol×6.02×10

23

molecules/mol=6.02×10

22

molecules