The molar mass of ammonium acetate is 77.083 g/mol. A student uses 0.100 mol of ammonium acetate in a chemical reaction. The student claims that the reaction uses (0.100 mol)(77.083 g/mol)=7.71 g(0.100 mol)(77.083 g/mol)=7.71 g of ammonium acetate, which has (7.71)(6.022×1023)=4.64×1024(7.71)(6.022×1023)=4.64×1024 molecules.

Question

The molar mass of ammonium acetate is 77.083 g/mol. A student uses 0.100 mol of ammonium acetate in a chemical reaction. The student claims that the reaction uses (0.100 mol)(77.083 g/mol)=7.71 g(0.100 mol)(77.083 g/mol)=7.71 g of ammonium acetate, which has (7.71)(6.022×1023)=4.64×1024(7.71)(6.022×1023)=4.64×1024 molecules.

In one to two sentences, explain the mistake that the student made and determine the correct number of molecules of ammonium acetate used in the reaction.

Answer 1

The mistake the student made is that they incorrectly calculated the number of molecules by multiplying the mass by Avogadro's number, which is only applicable for finding the number of atoms or molecules in a given mass of a single substance, not a compound like ammonium acetate. The correct number of molecules used in the reaction can be found by multiplying the number of moles by Avogadro's number: (0.100 mol)(6.022 x 10^23/mol) = 6.022 x 10^22 molecules.