Question

DUE TOMORROW!!!

Name Lab Instructor Date SS is Just a Four Letter Word UUUUUUU Pre Lab Assignment Experiment 3: HESS is Just a Four Le Consider the following reactions 1. CH(g) + 2 O2(g) - CO2(g) + 2 H20(1): AH=-890 kJ/mol 2. 2 CH (9) + 4 O2(g) – 2 CO2(g) + 4H2O(): AH=-1780 kJ/mo 3. CO2(g) + 2 H2O(l) - CHug) +2 02(g): AH=890 kJ/mol 4. 2 H2O(l) + 2 H2O(g): AH = 88 kJ/mol Quantitatively, how does the change in enthalpy AH for reaction #1 compare to the change in enthalpy for reaction #2? How would you expect the heat released by the combustion of 1.0 g of CH4 to compare to the heat released by the combustion of 2.00 g CHE? Based upon your answers to the 2 questions above would you conclude that AH is an extensive or intensive property? Explain. untitatively, how does the value of AH for reaction #1 compare to the AH for reaction #37 Based upon your answer to the your answer to the above question what can you say in general about the for a forward reaction compared to the AH for a reverse reaction

Answer 1

1) ∆H of reaction 2 is double of that of ∆H of reaction 1 because moles of each species get doubled.

2) Heat released on combustion of 2 g CH4 is double of that of heat released during combustion of 1 g CH4.

3) ∆H is extensive property because it depends on amount of substance taken.

4) ∆H of reaction 1 = - (∆H of reaction 3)

5) On reversing direction of reaction, sign of ∆H changes but magnitude remain same.

6) #1 : CH4(g) + 2O2(g) -> CO2(g) + 2H2O(l)

#4 : 2H2O(l) -> 2H2O(g)

#5 : CH4(g) + 2O2(g) -> CO2(g) + 2H2O(g)

∆H(#5) = -890+88 = -802 KJ/mol

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