Exercise 2 | Chemical Calculations

Here is a chemical reaction:

2 C6H6 + 15 O2 → 12 CO2 + 6 H2O

How many grams of CO2 are produced when 56 x 1015 molecules of C6H6 react?

From the chemical equation: 12 moles of CO2 are produced for 2 moles of C6H6.
nCO212 = nC6H62 ⇒ nCO2 = 6 nC6H6


nCO2 = 6x NC6H6NA = 6 x 56 × 10156.022 × 1023 = 5.581 x 10-7 mol


mCO2 = nCO2 x MCO2 = 5.581 x 10-7 x 44.0 = 2.456 x 10-5 g