Calculating Entropy Change When Burning A Substance

Question

Calculate the entropy change from burning 65.9 g of graphite to produce gaseous carbon dioxide, using the values in the table below.

Substance	S0 / J K-1 mol-1
C(graphite)	5.74
O2(g)	205.15
CO2(g)	213.79

The only equation I know is Delta S = the sum of S products - the sum of S reactants. But I don't know what to do with the 65.9g of graphite.

Answer 1

Write the balanced equation:

C + O₂ => CO₂

∑_prod - ∑_react = 213.79 - (5.74 + 205.15) = 2.9 J/K/mol

Note that the units represent per mole

65.9 g C x 1 mole/12.00 g x 2.9 J/K/mole = 15.9 J/K