Question

Calculate the mass of water formed when 4.6 g of oxygen gas reacts with excess hydrogen gas.

2H2+O2>2H2O

Answer 1

balanced equation

$2H_2+O_2>2H_2O$

Moles of oxygen = $given \ mass \over {molar \ mass}$

$={4.6 g\over 32 g}$

= 0.14 mole

2 moles O₂ gives 2 mole of H₂O

0.14 mole O₂ will give 0.14 mole of H₂O

Mass of H₂O = moles × molar mass

= 0.14×18

$= 2.52 g$ answer