Calculate the number of moles in (i) 12.046 × 1023 atoms of copper

1.	Calculate the number of moles in (i) 12.046 × 1023 atoms of copper (ii) 27.95 g of iron (iii) 1.51 × 1023 molecules of CO2
Answer» (i) 12.046 × 10²³ atoms of copper 6.023 × 10²³ atoms of copper = 1 mole 12.046 × 10²³ atoms of copper = \(\frac{1\times12.046\times10^{23}}{6.023\times10^{23}}\)= 2 moles of copper (ii) 27.95 g of iron 55.9 g of iron = 1 mole 27.95 g of iron = \(\frac{1}{55.9}\) x 27.95 = 0.5 mole of iron. (iii) 1.51 × 10²³ molecules of CO₂ No of mole = \(\frac{No.\,of\,molecules}{A\,vogadro\,number}\) = \(\frac{1.51\times10^{23}}{6.023\times10^{23}}\) = 0.25 mole of CO₂

Calculate the number of moles in (i) 12.046 × 1023 atoms of copper (ii) 27.95 g of iron (iii) 1.51 × 1023 molecules of CO2

Answer»

(i) 12.046 × 10²³ atoms of copper

6.023 × 10²³ atoms of copper = 1 mole

12.046 × 10²³ atoms of copper = \(\frac{1\times12.046\times10^{23}}{6.023\times10^{23}}\)= 2 moles of copper

(ii) 27.95 g of iron

55.9 g of iron = 1 mole

27.95 g of iron = \(\frac{1}{55.9}\) x 27.95 = 0.5 mole of iron.

(iii) 1.51 × 10²³ molecules of CO₂

No of mole = \(\frac{No.\,of\,molecules}{A\,vogadro\,number}\)

= \(\frac{1.51\times10^{23}}{6.023\times10^{23}}\)

= 0.25 mole of CO₂