Chemistry
posted by Brooke .
If it were determined that there were 6.391 x 10^22 atoms of H in an unknown sample of C2H4Cl2, how many milligrams would the unknown sample weigh?
Sorry for all the questions Dr. Bob.

So there are 6.391E22/4 molecules of C2H4Cl2. That divided by 6.022E23 = number of moles C2H4Cl2. Then moles x molar mass = grams. Convert to mg.

A sample of 0.43 moles of a metal M reacts completely with excess chlorine to form 18.23 grams of MCl.
How many moles of Cl are in the sample of MCl that forms?