How many atoms of Helium in a volume of :
4.25 x 10 ^ - 9 cubic meters @ 25 deg celcius?

Question

How many atoms of Helium in a volume of :
4.25 x 10 ^ - 9  cubic meters @ 25 deg celcius?

rushwr · Answer

Molar volume of a gas at standard temperature and pressure = 22.4 dm^3
To find the no. of moles = volume of the gas / molar volume of gas
no. of moles * avogadro's constant = no. of atoms

rushwr · Answer

Do u understand ?

biodelta · Answer

Thanks, I think so, just have to start by converting 25 C Vol to STP Vol?
or other way around? STP vol to 25 C vol? was going to use PV = NRT
but numbers seemed to big 10 ^21...Thanks

rushwr · Answer

As i said 
no. of moles = no. of atoms divided by avogadro's number
(subjecting no. of atoms : ) 
no. of atoms = no. of moles in to avogadro number
You should be knowing the avogadro number because it is a universal constant. 
therefore to find the no. of atoms we only need to find the no. of moles. 
Usually at Standard Temperature and Pressure (STP)  the molar volume of a gas is 22.4dm^3
Since we are already given with the volume of the gas what we have to do is to divide the volume of the gas by the molar volume of a gas at STP which is 22.4dm^3