Answer to Question #289310 in General Chemistry for jay jay

Question

Calculate the mass of hydrogen peroxide needed to obtain 0.460 L of oxygen gas at STP

2H₂O₂ --------> 2 H₂O + O₂ 

Answer 1

at STP volume of 1 mol of gas is 22.4 L. So 0.46 L of oxygen is 0.02 mol of oxygen. As we can see from reaction 1 mol of oxygen is obtained from 2 mols of peroxide. So 0.02 mol of oxygen is obtained from 0.04 mol of peroxide.

Mass of 1 mol of peroxide is 2+32=34 gram.

Then mass of 0.04 mol is 34x0.04=1.36 gram.