Question #f6570

1 Answer
Ayako_Sho
Feb 19, 2016

Simple,
Firstly, you want to find the number of moles in #7.6xx10^23# particles of helium, and also, the number of atoms is equal, it is in questions mainly to confuse you ,but remember, youre talking about Helium itself, thus there are particles of #7.6xx10^23#
So, as you probably already know
Number of Particles = Number of moles x Avogadro's constant
Since we re to find the number of moles
Number of moles = Number of Particles/Avogadro's Constant
#=7.6xx10^23//6.02xx10^23#
#=1.26#
1.26 moles in #7.6xx10^23# particles of helium
Now, since we are to calculate the mass, we will use this formula
No. of moles = #Mass//Molar Mass#
The molar mass of helium is 4.00g/mol
Rearranging this equation to our needs, we have
Mass = Number of moles x Molar Mass
Mass = #1.26xx4.00#
Mass = #5.04#
Thus, there is 5.04g of helium in #7.6xx10^23#

Hope this helps

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