Question

If the average adult is to exhale `"1.0 kg"` of `"CO"_2`, how much glucose was involved?

Answer 1

680 g C6H12O6

Explanation:

The average adult must convert 680 g of glucose to exhale 1.0 kg of CO₂.

First, write the balanced chemical equation.

C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O

You must make the following conversions:

mass of CO₂ → moles of CO₂→ moles of C₆H₁₂O₆ → mass of C₆H₁₂O₆

Mass of C₆H₁₂O₆ = `"1000 g CO"_2 × ("1 mol CO"_2)/("44.01 g CO"_2) × ("1 mol C"_6"H"_12"O"_6)/("6 mol CO"_2)× ("180 g C"_6"H"_12"O"_6)/("1 mol C"_6"H"_12"O"_6) = "680 g C"_6"H"_12"O"_6`

Note: The answer can have only 2 significant figures, because that is all you gave for the mass of CO₂. If you need more precision, you will have to recalculate.