i need help with a catalyzed decomposition problem?

Question

Calculate the number of moles of oxygen gas produced from the complete catalyzed decomposition of 6.20ml sample of a 3.5% solution of H2O2. The density of the 3.5% solution of H2O2 is 1.01 g/ml.

i cant figure out how to do this

Answer 1

The "complete catalyzed decomposition" is what Alfred Hitchcock used to call a "McGuffin." You're supposed to pay attention to Janet Leigh, while the story goes someplace else.

2H2O2 ===> 2H2O + O2

Atomic weights: H=1 O=16 H2O2=34 H2)=18

Let the hydrogen peroxide solution be called PS.

6.20mLPS x 1.01gPS/1mLPS x 3.5gH2O2/100gPS x 1molH2O2/34gH2O2 x 1molO2/2molH2O2 = 0.00322 moles O2 = 3.22 x 10^-3 moles O2