Question

What is the mass of 0.60 moles of Al?

Answer 1

It helps to map out how you will navigate through your unit analysis problem before setting it up.  

You are given moles and need grams.  What can be used as a conversion factor from moles to grams?  Molar mass.  We are working with aluminum, so we will need the molar mass of aluminum.  My Periodic Table tells me the molar mass of aluminum is approximately 27 g/mol.  Now we are ready to set up the unit analysis.

$0.60molAl(\frac{27gAl}{1molAl} )=16.2 gAl$

Moles must go on the bottom so that they cancel.  Notice how our number of significant figures is 2, so the answer must round to 16 g Al.

Answer:

16 grams