Question

3. 42 g of sucrose are dissolved in 18g of water in a beaker. The number of oxygen atoms in the solution are??

Answer 1

Molecular mass of sucrose=342 u

molar mass = 342 g

given mass =3.42 g

given mass in terms of molar mass = 1/100 of molar mass

No. of molecules in 1 mole =6.022*10^23

No. of molecules in given mass = 1/100 * 6.022*10^23=6.022*10^21

No.of oxygen atoms in 1 molecule of sucrose =11

No.of oxygen atoms in 6.022*10^21 molecules =11*6.022*10^21=6.6242*10^22atoms

Now,given water 18g

molecular mass of water = 18 u

given water = 18g = 1 mole

no.of oxygen atoms in 1 molecule of water = 1

No. of oxygen atoms in 6.022*10^23 molecules =1*6.022*10^23=6.022*10^23 atoms

Total no. of oxygen atoms inthe solution =6.022*10^23+0.66242*10^23

=6.68442*10^23 atoms