Answer: The number of molecules of gas the flask contains is [tex]0.674\times 10^{23}[/tex]
Explanation:
According to ideal gas equation:
[tex]PV=nRT[/tex]
P = pressure of gas = 1 atm (STP)
V = Volume of gas = 2.50 L
n = number of moles = ?
R = gas constant =[tex]0.0821Latm/Kmol[/tex]
T =temperature = 273K (STP)
[tex]n=\frac{PV}{RT}[/tex]
[tex]n=\frac{1atm\times 2.50L}{0.0821 L atm/K mol\times 273K}=0.112moles[/tex]
According to Avogadro's law:
1 mole of gas at STP contains =[tex]6.023\times 10^{23}[/tex] molecules
Thus 0.112moles of gas at STP contains = [tex]\frac{6.023\times 10^{23}}{1}\times 0.112=0.674\times 10^{23}[/tex] molecules
The number of molecules of gas the flask contains is [tex]0.674\times 10^{23}[/tex]