Help with Chemistry!?

  • Thread starter Thread starter Michael H
  • Start date Start date
M

Michael H

Guest
Calculate the mass of..

3 x 10^22 formula units of MgCl2
2.8 mol of Fe2(S04)3
1.2 x 10^24 formula units of Al2O3

To calculate the mass of compounds, would you need to find out the Relative Atomic Mass of these compounds? and also, would the equation for finding the mass of a compound me M = m x Na?

I really don't want people telling me the answer but just a guideline or
steps on how to do these problems.

Thank you.
 
1 mole = gfm of the compound. The gfm is the gram formula mass. The way I teach it is that you add up the atomic masses from the periodic table for the elements in the compound. Ex: H2O is 18g, since H is 1, and there are 2 of them, and oxygen is 16, so (1x2) + 16 equals 18.

1 mole also equals 6.02 x 10^23.

So....for the first and third problems you asked about, convert the formula units to moles by dividing by 6.02^23, and then multiply by the gfm.

For the second problem you have listed, since it is already in moles, you would just multiply by the gfm.
 
Back
Top