Question

Hydrogen peroxide is unstable and decomposes readily: 2H2O2(aq) → 2H2O(l) + O2(g) This reaction is accelerated by light, heat, or a catalyst. The concentrations of aqueous hydrogen peroxide solutions are normally expressed as percent by mass. In the decomposition of hydrogen peroxide, how many liters of oxygen gas can be produced at STP from 12.9 g of a 7.50% hydrogen peroxide solution?

Answer 1

Balanced equation:
2 H₂O₂(aq) ====> 2 H₂O(l) + O₂(g)
Reaction type: decomposition

Mass percentage of H2O2 = 7.5 %

Mass of H2O2 = 7.5 x 12.9 /100 = 0.9675 gm

Moles of H2O2 = 0.9675 / 34.01 = 0.02844 Moles

Moles of O2 produced =  0.01422 Moles

The formula is

PV=nRT

P = 1 atm V = ? n = 0.01422 Moles

R = 0.0821 L atm K-1 Mol-1 T = 273.15 K

V = 0.01422 x 0.0821 x 273.15 / 1 = 0.318 Liter or 318 ml

318 ml or 0.3188 Liter of oxygen gas can be produced at STP from 12.9 g of a 7.50% hydrogen peroxide solution