Question

Gaseous hydrogen and oxygen can be prepared in the laboratory from the decomposition of gaseous water. The equation for the reaction is2H2O(g) --> 2H2(g)+O2(g)Calculate how many grams of O2(g) can be produced from 42.6 grams of H2O(g).

Answer 1

• 75.5 g O₂ (g) can be produced from 42.6 g of H₂O (g)

Step-by-step explanation:

1) Balanced chemical equation (given):

• 2H₂O(g) → 2H₂(g) + O₂(g)

2) Mole ratios:

• 2 moles H₂O(g) : 2 moles H₂(g) : 2 moles O₂(g)

3) Calculate the number of moles of reactant (H₂0):

• number of moles = mass in grams / molar mass

• molar mass of water: 18.015 g/mol

• mass in grams of water: 42.6 g

• number of moles = 42.6 g / 18.05 g/mol = 2.36 moles H₂O

4) Set a proportion using the mole ratio O₂ to H₂O and the actual number of moles of H₂O:

• 2 moles O₂ / 2 moles H₂O = x / 2.36 moles H₂O

• x = 2.36 moles O₂

5) Convert 2.36 moles O₂ to grams:

• mass in grams = number of moles × molar mass

• mass = 2.36 moles × 32.00 g/mol = 75.5 g O₂

Answer 2

37.87 g of oxygen can be produced from the 42.6 grams of H2O

Step-by-step explanation:

From the question, the following equation shows the decomposition of gaseous water

2H₂O(g) ⇒ 2H₂(g) + O₂(g)

where atomic mass of hydrogen is 1 g/mol and atomic mass of oxygen is 16 g/mol

The molar mass of 2H₂O is;

2[(2 ×1) + (16 × 1)]

2(2+16) = 36 g

The molar mass of O₂ is;

2 × 16 = 32 g

Hence, it can be deduced that 36 g of water produced 32 g of oxygen, hence 42.6g of water will produce how many grams of oxygen (represented as X)

∴ 36 ⇒ 32

42.6 ⇒ X

X = 42.6 × 32/36

X = 37.87 g