Answer the following question based on the previously determined balanced chemical equation (H2O2--> 2H2O + O2)

Question

Answer the following question based on the previously determined balanced chemical equation for the decomposition of hydrogen peroxide. Express your answer to two decimal places.

How many moles of H₂O₂ are needed to make 33.85 grams of O₂?

Answer 1

First you need to check if the equation is actually balanced, in this case it is not.

Left Hand Side (LHS) has two hydrogen and two oxygen.

Right Hand Side (RHS) has four hydrogen and four oxygen.

So we balance the equation with 2, 2, 1 giving us.... 2 H₂O₂ --> 2 H₂O + O₂

This way we know that for each molecule of O₂ made in this reaction we need two molecules of H₂O₂

We can calculate the molar mass of O₂ and H₂O₂ as 32g/mol and 34.02g/mol

Now we are finally ready to calculate...

1) (33.85 g O2) x (1mol O₂ / 32 g O₂) = 1.058 mol O₂

2) From our balanced equation we know that every mole of O₂ requires 2 moles of H₂O₂

so 2 x 1.058 mol = 2.116 mol H₂O₂

Answer 2

First of all, the balanced equation is:

2H₂O₂ --> 2H₂O + O₂

How many moles of H₂O₂ are needed to make 33.85 grams of O₂?

Convert 33.85 g of O₂ to moles:

(33.85 g O₂/1) * (1 mole O₂/31.96 g O₂) = 1.059 moles O₂

Convert moles O₂ to mole H₂O₂

(1.05 moles O₂/1) * (2 mole H₂O₂/1 mole O₂) = 2.10 moles H₂O₂