Question

C3H8 + 5 O2 - - - - - - - - > 3 CO2 + 4 H2O

Calculate how many molecules of CO2 are produced when 2.3 x 106 atoms of O2 are reacted.

Answer 1

A mole of oxygen atoms (with the formula O) contains 6.02×10²³ O atoms. A mole of oxygen molecules (formula O₂) contains 6.02×10²³ O₂ molecules – that is, 2×6.02×10²³ O atoms.

In this problem there are (2.3×10⁶) /2 = 1.15×10⁶ molecules of O₂.

Proportion according to the reaction:

5 – 3

1.15 ×10⁶ – x

x = 0.69 ×10⁶ molecules of CO₂

Answer: 6.9 ×10⁵ molecules