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12. Propane gas (C,Hs, molar mass is 44.10 g/mol) is typically used as a fuel in

ID: 575438 • Letter: 1

Question

12. Propane gas (C,Hs, molar mass is 44.10 g/mol) is typically used as a fuel in gas grills and a key component in the grilling of bratwurst during the summertime. The combustion reaction of propane is given below C'H,(g) + 502(g) 3C0; (g) + 4 H2O(g) Nr--344 kJ For successful preparation of a bratwurst requires boiling them in a heterogeneous mixture of beer and onions. There fore, one would first need to bring the beer and onions to a boil. Assume the beer (and the onions together) has the same specific heat as water, 4, 182 J g· How many grams of propane would be required to raise the temperature of 1413 grams of beer by 78.0 ?

Explanation / Answer

12 )

mass of beer = 1413 g

specific heat = 4.182 J / g oC

temperature = 78.0 oC

Q = m Cp dT

   = 1413 x 4.182 x 78

Q = 460914.95 J

Q = 460.9 kJ

delat H = - 2044 kJ

delta H = - Q / n

- 2044 = - 460.9 / n

n = 0.2255

moles of propane = 0.2255

mass of propane = 9.944 g