QAChemistry › For a particular isomer of C8H18, The following reaction produces 5093.7 KJ of heat
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For a particular isomer of C8H18, The following reaction produces 5093.7 KJ of heat

For a particular isomer of C8H18, The following reaction produces 5093.7 KJ of heat per mole of C8H18(g) consumed under standered conditions. What is the standard enthalpy of formation of this isomer of C8H18(g)?
A

First, let’s define the standard enthalpy values (H):

02(g) = 0 kj/mol
CO2 (g) = -393.5 kj/mol
H20(g) = -241.8 kj/mol

According to the instructions, heat per mole produced (H) equals 5094 kj

Therefore, -5094 kj is your H total.

H (reaction) = H (products) – H (reactants)

Let’s set the value of H for C8H18(g) to x (unknown)

then, -5094 kj = [8(CO2) + 9(H2O)] – [x +12.5(O2)]

If we use the standard enthalpy values,

5094kj = [8(-393.5) + 9(-241.8)] – [x + 12.5(0)]

-5094 kJ = -5324.2 – x

Answer: x = -230 kj/mol

8 months ago
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