Converting Between Grams and Moles!

The mole really isn't that hard; you simply need to take and do the work! With practice, you'll master the concepts. Today, we're converting between moles and mass. When we do so, we use molar mass as the conversion factor. Be sure to cancel the appropriate units! 

EXAMPLES
-How many grams is there in 1.5 mol of O₂ ? -How many moles are there in 115g of Fe₂O₃ ? -A sample of HCL contains 0.54 mol. How many grams of HCL is this?-How many grams are present in a 2.5g sample of ammonium phosphate?
-How many grams are needed to make 2.5x10^-3 mol of Cobaltous Chloride hexahydrate?

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-A compound is made of phosphorous and chlorine. It is found to contain 0.200 mol and has a mass of 27.5g. Determine the molar mass of the compound. Suggest a possible formula.
This last one's a toughy; it involves trial and error. To find the molar mass, divide 27.5g by 0.200mol. x(31.0) + y(35.5) should equal 137.5g/mol. Then, use trial and error to determine that a possible formula is PCL₃ [one Phosphorous (ie. the x value) and three Chlorine (ie. the y value)].

Next time: converting between moles and volume.


NOTE: DO NOT FORGET ABOUT SIGNIFICANT DIGITS!!

Next time: Converting Between Volume and Moles!