If 0.123 L of h2o2 are completely decomposed, how many moles of oxygen gas will be produced? The density of hydrogen peroxide is 1.45 g/ml

Answer 1

First, let's write the correctly balanced equation

2H₂O₂ ==> 2H₂O + O₂

Next, find the mass of H₂O₂

0.123 L x 1000 ml / L x 1.45 g / ml = 178.35 g H₂O₂

Convert this to mol H₂O₂

178.35 g x 1 mol / 34.01 g = 5.244 mol H₂O₂

Finally, find mols O₂ produced from 5.244 mols H₂O₂

5.244 mol H₂O₂ x 1 mol O₂ / 2 mol H₂O₂ = 2.62 mol O₂ formed (3 sig. figs.)

Answer 2

There is one mole of O₂ in one mole of H₂O₂ that is completely decomposed. The usual equation for decomposition of 1 mole of hydrogen peroxide is to one mole of water and 1/2 mole of O₂ .Now just use factor labeling to connect the extensive variable .123 liter of H₂O₂ to moles of O₂ :

.123 l H₂O₂ (1000 ml/1liter)(1.45 g/ml)(1 mole O₂/1mole H₂O₂) = moles H₂O₂

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