2a. Consider the combustion of propane gas, Propane is often used for gas grills
ID: 1016512 • Letter: 2
Question
2a.
Consider the combustion of propane gas,
Propane is often used for gas grills and is typically purchased by filling a propane tank with 20 pounds of propane. What is the enthalpy change when 10 pound of propane is burned? Use the conversion 1 lb = 454 g and express your answer in scientific notation. For example use 2.3e-5 to indicate a number such as 2.3 x 10-5.
__________kJ
What is the enthalpy change for
Hint, compare this equation to the combustion equation for propane.
________kJ
2b.
Consider the following thermochemical equation:
kJ
2c.
The reaction would be extensive at ---Select--- at high temperatures at low temperatures at no temperature at all temperatures .
C3H8(g) + 5O2(g) 3CO2(g) + 4H2O(l) Ho = -2,220 kJ/molExplanation / Answer
2a]
given 10 pounds of propane
10 pounds = 4540 gms of propane
moles of propane = 4540 / 44 = 103.18
for 1 mole of propane --- > delta H values is -2,220 kJ/mol
103.18 moles of propane have delta H value = -226996 KJ/mol
the enthalpy change in reverse reaction
3 moles of CO2 = delta H value is 2,220 kJ/mol
15 moles of CO2 = 5 * delta H value ==> 11100 KJ/mol
2b] 1mole of CaCO3 absorbs 178 KJ
CaCO3 M.W = 100 gms
moles = 33/100 = 0.33
1 mole 178
0.33 ==> 58.74 KJ/mol
2c]
delta H = Bond energies of reactants - bond energies of products
delta H = 6 N-H bond energy - [3 H-H bond energy + N-N bond energy ]
delta H = 78 KJ/mol
delta S= positive and large
since no. of molecules in products side are more than reactants
therefore randomness increases
the reaction would be extensive at high temperatures