Question

1. When .514 g of C₁₂H₁₀ undergoes combustion in a bomb calorimeter, the temperature increases from 25.8^oC to 29.4^oC. The heat capacity of the bomb and all of its contents is 5.86 kJ/^oC.

1. What is the heat released per mole of C₁₂H₁₀?
2. Is the number you calculated ΔE or ΔH? Why?
3. Is ΔE = ΔH for this reaction? Why?

Balanced reaction: 2 C₁₂H₁₀ (s) + 29 O₂ (g) → 24 CO₂ (g) + 10 H₂O (g)

4. If ΔE and ΔH are not equal, which one is more negative? Why?

Answer 1

(a) equation for the Ciatio Combustion The balanced is follows - as 10 H₂O(g) 24C02(g) 2012 H10 (s) + 29 0₂ (g) of masses of mass molan C12H10 154 glmole [ atomic respectively (in g gratum 1 and H are 12 and unit) mole Cialio ie 0.514 4 C 12 Hlo 0.514 154 innease the the from heat nequined 25.8 oC 29.4 oc temperature (heat capacity of in temperature) (5.86 kJ/°c) у inmease Calorimeter) ( 29.4 – 25.8 °C) 21.096 KT combustion of 10:54 released for hence heat 21.096 KI mole Cialio 21.096 Pen (12 Hio heat released mole 0.514 154 KJ/mol 6320.59 KTlmol is 6320.59 Cialio heat released Pen mole of here, Kilmol. happens at Constant reaction 6) change is bomb Calonimelen, volume. Hence, the internal Change Calculaled energy energy

Change in internal energy (Atland change in enthally (oh) nelated as AH = tang RT gaseous moles of gaseous Ама moles of a Product) - ( total meattort) reactant 2 = of C12Ho, moles gaseous Pen mole 12 and of со, оле and H₂O moles gaseous and 5 respectively. 2.5 20 Ang = 12+5 - 29 to; AH ŁA As Ang RT equal orie not AH and hence, negative symbol is d 6320.59 kJ/mole tone, have been released energy as used Positive of ane each Ang R is mone eative. 4H 1) more Hence, negative,