Atom economy = (total Mr of desired product ÷ total Mr of all products) x 100
Hydrogen gas is obtained from methane in a process called steam-methane reforming. Calculate the atom economy of this reaction.
Equation Of Reaction:
CH4 (g) + H2O (g) → CO (g) + 3H2 (g)
Step 1 Calculate the total Mr of all the products:
Total Mr = 28 (CO:12 + 16) + (3H2: 6 x 1) = 34
Step 2 Calculate the Mr of the desired products:
Mr of 3H2 (6 x 1) = 6
Step 3 Calculate the atom economy:
Atom economy = (6 ÷ 34) x 100 = 17.6%
Therefore in this process 82% by mass of reactants is wasted.