Question

Calculate the number of moles in each of the following.
(i) 392 g of sulphuric acid
(ii) 44.8 litres of sulphur dioxide at N.T.P.
(iii) 8g of calcium

Answer 1

Answer:

Number of moles = Mass of substance / Mass of one mole.

(i)4 mol

(ii)2 mol

(iii)0.2 mol

Explanation:

(i)molar mass of H2HSO4=98 g

98 g H2HSO4=1 mol

392 g of H2HSO4=(1 mol/98 g)*(392 g)

                              = 4 mol

(ii)22.4 L of S02 at NTP=1 mol

44.8 L of S02 at NTP=(1 mol/22.4 L)*44.8 L)

                                  = 2.0 mol

(iii)atomic mass of Ca=40 g

40 g of calcium=1 mol

8 g of calcium=(1 mol)*(8g/40 g)

                       =0.2 mol

Answer 2

Number of moles = Mass of substance / Mass of one mole.

(i)4 mol

(ii)2 mol

(iii)0.2 mol

Explanation:

(i)molar mass of H2HSO4=98 g

98 g H2HSO4=1 mol

392 g of H2HSO4=(1 mol/98 g)*(392 g)

                             = 4 mol

(ii)22.4 L of S02 at NTP=1 mol

44.8 L of S02 at NTP=(1 mol/22.4 L)*44.8 L)

                                 = 2.0 mol

(iii)atomic mass of Ca=40 g

40 g of calcium=1 mol

8 g of calcium=(1 mol)*(8g/40 g)

                      =0.2 mol