Step 1. Write the balanced chemical equation
#M_text(r):color(white)(mmmmmm) 34.01"#
#color(white)(mm)"H"_2 + "O"_2 → "H"_2"O"_2#
Step 2. Calculate the moles of #"O"_2#
#"Moles of O"_2 = 3.56 × 10^28 color(red)(cancel(color(black)("molecules O"_2))) × "1 mol O"_2/(6.022 × 10^23 color(red)(cancel(color(black)("molecules O"_2)))) = "59 120 mol O"_2#
Step 3. Calculate the moles of #"H"_2"O"_2#
#"Moles of H"_2"O"_2 = 59 120 color(red)(cancel(color(black)("mol O"_2))) × ("1 mol H"_2"O"_2)/(1 color(red)(cancel(color(black)("mol O"_2)))) = "59 120 mol H"_2"O"_2#
Step 4. Calculate the mass of #"H"_2"O"_2#
#"Mass of H"_2"O"_2 = "59 120" color(red)(cancel(color(black)("mol H"_2"O"_2))) × ("34.01 g H"_2"O"_2)/(1 color(red)(cancel(color(black)("mol H"_2"O"_2)))) = 2.01 × 10^6 color(white)(l)"g H"_2"O"_2#
