Question

18 gram of sucrose is dissolved in 180 gram of water. Calculate the number of oxygen atoms in the solution.​

Answer 1

We know, molecular mass of sucrose is 342 g/mol.

So, number of moles in 18 g is :

$n_1 = \dfrac{342\ g/mol}{18\ g}\\\\n_1 = 0.053 \ moles$

Also, number of moles of water is :

$n_2 = \dfrac{180}{18} \\\\n_2 = 10 \ moles$

We know, 1 mole of sucrose contain 11 moles of oxygen.

So,

$n' = 0.053\times 11\\\\n'= 0.583\ moles$

1 mole of water contain 1 mole of oxygen .

So, moles of oxygen in water are :

$n'' = 10\ moles$

Total number of moles, $n' + n'' = 10.583 \ moles$ .

Number of oxygen atoms are :

$N = 6.022 \times 10^{23}\times 10.583\\\\N = 6.37 \times 10^{24}$

Hence, this is the required solution.