Question

Electrolysis of water produces its constituent elements, hydrogen and oxygen. This process is represented by the following balanced chemical equation:

2 H2O(l) → 2 H2(g) + O2(g).

If 8.05 grams of oxygen gas was produced in the reaction, how many molecules of water were decomposed?

Do enter the coefficient of the answer only. Do NOT include the unit in final answer.

_______________________________ × 1023 H2O molecules.

Answer 1

Answer:

3.011 × 10²³

Explanation:

Given data:

Mass of oxygen produced = 8.05 g

Molecules of water decomposed = ?

Solution:

Balance chemical equation:

2H₂O   →   2H₂  + O₂

Number of moles of oxygen produced:

Number of moles = mass/molar mass

Number of moles = 8.05 g/ 32 g/mol

Number of moles = 0.25 mol

Now we will compare the moles of water with oxygen.

              O₂             :             H₂O

               1               :               2

              0.25         :            2×0.25 =0.5 mol

0.5 moles of water were decomposed.

Molecules of water decomposed:

1 mole = 6.022× 10²³ molecules of water

0.5 mol ×6.022× 10²³ molecules of water/ 1mol

3.011 × 10²³ molecules of water