To convert from grams to moles, we must divide the given grams by the molar mass of the element. The molar mass of aluminum Sn is 118.71g/mol. So the moles of Sn will be:
[tex]molSn=givengSn\times\frac{1molSn}{MolarMass,gSn}[/tex][tex]molSn=20.3gSn\times\frac{1molSn}{118.71gSn}=0.17molSn[/tex]Answer: 20.3 grams of Sn are equal to 0.17 moles of Sn
