How many liters of oxygen at stp are needed to react with 5.2 * 10 to the 22nd power molecules of hydrogen sulfide?

For the reaction H2S + 2 O2 -> H2SO4

starting with 5.2 x 10^22 molecules of H2S we can calculate the number of moles H2S by dividing by 6.02 x 10^23

We have 0.086 moles H2S

1 mole of H2S reacts with 2 moles of O2 so we need 0.17 moles of O2

1 mole of all gases at stp occupy 22.4 liters of space

.17 x 22.4 = 3.08 liters of O2 needed to react with 5.2 x 10^22 molecules of H2S