Data

Mole of Oxygen = 8 moles
Mole of Hydrogen = 5moles
Asked: Volume of water formed.

Chemical equation for the reaction
2H_2(g) + O_2(g) → 2H₂O_(l)
2 moles: 1 mole: 2 moles

To make mole ratio

For H₂ = 5 moles / 2
= 2.5 mole (limiting reaction)

For O₂ = 8 Moles / 1 mole
= 8 moles (excess reactant)

Volume of water formed

Water was formed by using limiting reactant which in hydrogen gas (H₂). So, we do mole equivalent

2 moles of H₂ Ξ 2 moles of H₂O
5 moles of H₂ Ξ ?? of H₂O

= (5 mole × 2 moles) / 2 moles
= 5 mole of H₂O was formed

Volume of water = mole × molar volume
= 5 moles × 22.4dm³/mole
= 112dm³

112dm³ of water was produced at S.T.P.