Answer:

To solve this problem, you can follow these steps:

a. Calculate the moles of water (H2O) formed when 2.5 grams of H2O2 decomposes.

The molar mass of H2O2 is 34.0147 g/mol. It contains two moles of hydrogen (H) and two moles of oxygen (O) per mole of H2O2.

Molar mass of H2O2 = 2(1.00794 g/mol) + 2(15.999 g/mol) = 2.01588 g/mol + 31.998 g/mol = 34.01388 g/mol (approximately 34.014 g/mol)

Now, calculate the moles of H2O2:

Moles of H2O2 = Mass (g) / Molar mass (g/mol)

Moles of H2O2 = 2.5 g / 34.014 g/mol ≈ 0.0735 moles

Since H2O2 decomposes into H2O and O2 in a 1:1 molar ratio, the number of moles of water (H2O) formed is also 0.0735 moles.

b. Calculate the mass of oxygen (O2) liberated:

The molar mass of O2 is 32.00 g/mol (16.00 g/mol for each oxygen atom).

Moles of O2 = Moles of H2O2 (from part a)

Moles of O2 = 0.0735 moles

Now, calculate the mass of O2:

Mass of O2 = Moles of O2 x Molar mass of O2

Mass of O2 = 0.0735 moles x 32.00 g/mol = 2.352 g

So, when 2.5 grams of H2O2 decompose, approximately 0.0735 moles of water (H2O) are formed, and 2.352 grams of oxygen (O2) are liberated.

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