Question

Calculate the number Of moles, molecules and total number of atoms present in $1.1\times {10}^{-4}kg{CO}_2$ [C=12, O=16]

Answer 1

No. of moles of ${CO}_2=\frac{wt.of{CO}_2}{m/wt.of{CO}_2}$

wt. of ${CO}_2=1\times {10}^{-4}kg=1\times {10}^{-4}\times {10}^{3}gm$

$=$0.1gm no. of moles of ${CO}_2=\frac{0.1}{44}=0.002273$ moles

1 mole. contain $6.023\times {10}^{23}$

molecule So 0.002273 more contain

$=0.002273\times 6.023\times {10}^{23}$

$=0.01369\times {10}^{23}$

$=1.369\times {10}^{29}moleculsof{CO}_2$

The number of atoms are 3.

Thus the total number of atoms$=3\times 1.369\times {10}^{29}=4.107\times {10}^{29}$