Hi!
The answer would be ~ 3.58
Explanation
You will need to use the simple formula of finding the number of moles, given the mass of the compound, which is:
number of moles of compound = mass of compound / Mr of compound
The mass in this equation is the mass of the compound you have/ are considering.
The Mr is the sum of the atomic masses of each element in the compound.
To proceed with this, you need to have two of the following values:
Mass : 340g
Mr of MgCl2 : 95
Number of moles : ?
Substituting the respective values in the equation:
number of moles = mass / Mr
number of moles = 340 / 95
number of moles = 3.58
Hope this helps!
