Question

A flask contains 4.4g of co2 gas clculate 
1)how many  amount of co2 does it contain.
2)how many molecules of co2 gas are present in sample.
3)how many atoms of oxy gen are present in the given sample.[atomic mass of c=12u,o2=16u]

Answer 1

Molecular mass of co2 gas=44g[Atomic mass of c=12g,atomic mass of o=16g]
1).44g=1mole
     4.4g=1/44*4.4=0.1 mole
2).1mole=6.022*10^23molecules
   0.1 mole=6.022*10^23*0.1molecules=6.022*10^22molecules
3).2atoms

Answer 2

Answer: 1) 0.1 moles

2) $0.6023\times 10^{23}$ molecules of $CO_2$

3) $1.2046\times 10^{23}$ atoms of $O_2$

Explanation:

1) To calculate the moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\textMolar mass}}$

$\text{Number of moles of carbon dioxide}=\frac{4.4g}{44g/mol}=0.1 moles$

2) According to avogadro's law, 1 mole of every substance occupies 22.4 Liters at STP and contains avogadro's number $6.023\times 10^{23}$ of particles.

Thus 1 mole of $CO_2$ contains = $6.023\times 10^{23}$ molecules of $CO_2$

0.1 moles of $CO_2$ contains = $\frac{6.023\times 10^{23}}{1}\times 0.1=0.6023\times 10^{23}$ molecules of $CO_2$

3) 1 mole of $CO_2$ contains = $2\times 6.023\times 10^{23}=12.046\times 10^{23}$ atoms of $O_2$

0.1 mole of $CO_2$ contains = $\frac{12.046\times 10^{23}}{1}\times 0.1=1.2046\times 10^{23}$ atoms of $O_2$