In three moles of ethane $\left(\mathrm{C}_{2} \mathrm{H}_{6}\right)$, calculate the following:
Question.

In three moles of ethane $\left(\mathrm{C}_{2} \mathrm{H}_{6}\right)$, calculate the following:

(i)Number of moles of carbon atoms.

(ii)Number of moles of hydrogen atoms.

(iii)Number of molecules of ethane

Solution:

(i) 1 mole of $\mathrm{C}_{2} \mathrm{H}_{6}$ contains 2 moles of carbon atoms.

$\therefore$ Number of moles of carbon atoms in 3 moles of $\mathrm{C}_{2} \mathrm{H}_{6}$

= 2 × 3 = 6

(ii) 1 mole of $\mathrm{C}_{2} \mathrm{H}_{6}$ contains 6 moles of hydrogen atoms.

$\therefore$ Number of moles of carbon atoms in 3 moles of $\mathrm{C}_{2} \mathrm{H}_{6}$

$=3 \times 6=18$

(iii) 1 mole of $\mathrm{C}_{2} \mathrm{H}_{6}$ contains $6.023 \times 10^{23}$ molecules of ethane.

$\therefore$ Number of molecules in 3 moles of $\mathrm{C}_{2} \mathrm{H}_{6}$

$=3 \times 6.023 \times 10^{23}=18.069 \times 10^{23}$
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