For the following combustion reaction CH₃CH₂CH₂COOH(l) + 5O₂(g) → 4CO₂(g) + 4H₂O(g) ∆H

Question

For the following combustion reaction CH₃CH₂CH₂COOH(l) + 5O₂(g) → 4CO₂(g) + 4H₂O(g) ∆H = -2.18 × 10³ kJ When a 8.42-g sample of butyric acid (molar mass = 88.10 g/mol) is burned, how much energy (in kJ) is released as heat?

Answer 1

C₄H₈O₂₍l) + 5O₂(g) ==> 4CO₂(g) + 4H₂O(g) ... balanced equation ... ∆H = -2180 kJ.

This tells us that the reaction as written gives off 2180 kJ of heat for every 1 mole of C₄H₈O₂ combusted.

We need to find out how many moles 8.42 g is.

8.42 g C₄H₈O₂ x 1 mol / 88.10 g = 0.09557 moles C₄H₈O₂

Now we can find the heat generated:

0.09557 mols x -2180 kJ / mol = -208.3 kJ. The minus sign in front of the answer indicates heat is being released.