Hydrocarbons, compounds containing only carbon and hydrogen, are important in fuels. The heat of combustion of cyclopropane, C3H6, is 499.8 kcal/mol. ?

Write a balanced equation for the complete combustion of cyclopropane

How much energy is released during the complete combustion of 446 grams of cyclopropane ?

_ kcal

2 Answers
anor277
Mar 7, 2018

We write the stoichiometric combustion reaction...

Explanation:

#C_3H_6(g) + 9/2O_2(g) rarr 3CO_2(g)+3H_2O(l)+Delta#

...and here #DeltaH_"combustion"^@=-499.8*kcal*mol^-1#.

And so we interrogate the molar quantity of cyclopropane...

#(446*g)/(42.08*g*mol^-1)=10.6*mol#...and given the formation of stoichiometric carbon dioxide and water....we get....

#Delta=10.6*molxx499.8*kJ*mol^-1-=5297.3*kJ#...

Cherry B.
Mar 7, 2018

Balanced chemical combustion equation:
# #
#2C_3H_"6(g)" + 180_"2(g)" -> 6CO_"2(g)" + 6H_2O_"(l)"#
# #
# #
#10614.8# kCal released during combustion of 446 grams of #C_3H_6#.

Explanation:

Set up balanced equation:
# #
#2C_3H_6 + 180_2 -> 6CO_2 + 6H_2O#
# #
# #
Use dimensional analysis:
# #
#(446g C_3H_6 )# #((1molC_3H_6)/(42g))# #((2mol C_3H_6)/(1mol C_3H_6))# # ((499.8 kCal)/(molC_3H_6))# #=#
# #
#10614.8kCal#

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