The equation for the reaction of carbon and nickel dioxide is: NiO + C ----> CO + Ni Calculate the percentage atom economy of this reaction to produce nickel to 3 significant figures.

Using a periodic table, you can find that: Molecular mass of carbon: 12Molecular mass of nickel: 59Formula mass of nickel oxide: 75 (=59+16)
Mass of all the reactants = 12+75=87Mass of the product we want (nickel)=59
Percentage mass = mass of all reactants/mass of product we want x 100 = (59/87)x100=67.816%
The question asks for the answer to 3 significant figures which means the first three numbers that aren't zero, therefore the answer is 67.8%