Question

which of the following sample contains the smallest number of atoms. a)1g of CO2. b)1g of C8H18. c)1g of C2H6. d)1g of LiF. explain how​

Answer 1

Answer : The sample contains the smallest number of atoms will be, 1 g of $C_8H_{18}$

Explanation :

(a) 1 g of $CO_2$

First we have to calculate the moles of the given sample.

$\text{Moles of }CO_2=\frac{\text{Mass of }CO_2}{\text{Molar mass of }CO_2}=\frac{1g}{44g/mole}=0.023moles$

Now we have to calculate the number of atoms.

As, 1 mole of $CO_2$ contains $6.022\times 10^{23}$ number of atoms

So, 0.023 mole of $CO_2$ contains $0.023\times 6.022\times 10^{23}=1.38\times 10^{22}$ number of atoms

(b) 1 g of $C_8H_{18}$

First we have to calculate the moles of the given sample.

$\text{Moles of }C_8H_{18}=\frac{\text{Mass of }C_8H_{18}}{\text{Molar mass of }C_8H_{18}}=\frac{1g}{114g/mole}=0.0088moles$

Now we have to calculate the number of atoms.

As, 1 mole of $C_8H_{18}$ contains $6.022\times 10^{23}$ number of atoms

So, 0.0088 mole of $C_8H_{18}$ contains $0.0088\times 6.022\times 10^{23}=5.29\times 10^{21}$ number of atoms

(c) 1 g of $C_2H_6$

First we have to calculate the moles of the given sample.

$\text{Moles of }C_2H_6=\frac{\text{Mass of }C_2H_6}{\text{Molar mass of }C_2H_6}=\frac{1g}{30g/mole}=0.033moles$

Now we have to calculate the number of atoms.

As, 1 mole of $C_2H_6$ contains $6.022\times 10^{23}$ number of atoms

So, 0.033 mole of $C_2H_6$ contains $0.033\times 6.022\times 10^{23}=1.98\times 10^{22}$ number of atoms

(d) 1 g of $LiF$

First we have to calculate the moles of the given sample.

$\text{Moles of }LiF=\frac{\text{Mass of }LiF}{\text{Molar mass of }LiF}=\frac{1g}{26g/mole}=0.038moles$

Now we have to calculate the number of atoms.

As, 1 mole of $LiF$ contains $6.022\times 10^{23}$ number of atoms

So, 0.038 mole of $LiF$ contains $0.038\times 6.022\times 10^{23}=2.28\times 10^{22}$ number of atoms

From this we conclude that, 1 g of $C_8H_{18}$ sample contains the smallest number of atoms.

Hence, the sample contains the smallest number of atoms will be, 1 g of $C_8H_{18}$