K. How many amu of H2O and CO2 can be made from 64 amu of CH4 and excess O2? 1. H2O 2. CO2?

1.
Molecular mass of CH₄ = (12 + 1×4) amu = 16 amu
Molecular mass of H₂O = (1×2 + 16) amu = 18 amu
Molecular mass of CO₂ = (12 + 16×2) amu = 44 amu

Balanced equation for the reaction:
CH₄ + 2O₂ → CO₂ + 2H₂O
Molecular ratio CH₄ : H₂O = 1 : 2

No. of molecules of CH₄ reacted = (64 amu) / (16 amu/molecule) = 4 molecules
No. of molecules of H₂O made = (4 molecules) × (2/1) = 8 molecules
Mass of H₂O made = (8 molecules) × (18 amu/molecule) = 144 amu

2.
Molecular ratio CH₄ : CO₂ = 1 : 1
No. of molecules of CO₂ made = (4 molecules) × (1/1) = 4 molecules
Mass of CO₂ made = (4 molecules) × (44 amu/molecule) = 176 amu

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Method 2:

1.
(64 amu CH₄) × (1 molecule CH₄ / 16 amu CH₄) × (2 molecule H₂O / 1 molecule CH₄) × (18 amu H₂O / 1 molecule H₂O)
= 144 amu H₂O

2.
(64 amu CH₄) × (1 molecule CH₄ / 16 amu CH₄) × (1 molecule CO₂ / 1 molecule CH₄) × (44 amu CO₂ / 1 molecule CO₂)
= 176 amu CO₂