Question

what is the mass of oxygen required to react completely with 15 gram of H2 gas to form water​

Answer 1

When free oxygen reacts with hydrogen the reaction is as follows-

2H2 + O2 = 2H2O


2 moles of hydrogen + 1 mole of oxygen → 2 moles of water

1 moles of hydrogen reacts with 1/2 mole of oxygen gas


For H2

W1 = 15g

M1 = 2×1 = 2g

n1 = W1/M1 = 15/2 moles



For O2

n2 = 0.5 × 15/2 = 15/4 moles

M2 = 16×2 = 32g

W2 = n1×M1 = 15/4 × 32 = 120g



Theoretically, mass of oxygen reacted is 120 g.