on the periodic table it shows the molecular weight of all the elements and what you do is add all the numbers together:
CaCl2=40.08+35.45x2=110.98g/mol
*Ca(NO3)2=40.08+14.01x2+16x6=164.1g/mol
*Ca(OH)2=40.08+16x2+1.008x2=74.096g/mol
CaSO4=40.08+32.06+16x4=136.14g/mol
BaCl2=137.33+35.45x2=208.23g/mol
*these 2 require you to distribute the 2 into each of the elements.