Question

13. Propane burns in air according to the following equation:

C3H8 (g) + 5 O2 (g) → 3 CO2 (g) + 4 H2O (g) ∆H = -2043 kJ

If 5.00 g of propane are reacted at a constant pressure of 1.15 atm leading to a change in volume of +8.6 L, calculate ∆E and the work done (in kJ). (MM C3H8 = 44.09 g/mol).

Using the information given (∆Hrxn = -2043 kJ) and any needed values from you text, calculate the ∆H o f for propane (C3H8).

Answer #1

Ans:

C_{3}H_{8} (g) + 5 O_{2} (g) → 3
CO_{2} (g) + 4 H_{2}O ∆H = -2043 kJ

P = 1.15 atm, w = 5 gm, ∆V = 8.6 L, MW of C_{3}H_{8
=} 44.06 g/mol

1) As system is doing work on the surroundings,

W = - P∆V = - 1.15 atm X 8.6 L = - 9.89 X 0.101325 KJ

Therefore, W = - 1.0021 KJ.

2) ΔH_{reaction} = q_{at constant pressure} =
q_{reaction}

Hence, q = - 2043 KJ

∆E = q + W = -2043 + (-1.0021)

= - 2.044 X 10^{3} KJ.

3) ∆H_{o} = 5 X 10^{-3} kg X 1000 g/1 kg X 1
mol/44.09 g X – 2043 KJ/1 mol

= - 2.316 X 10^{2} KJ.

When 1.000 g of propane gas (C3H8) is burned at 25ºC and 1.00
atm, H2O (l) and CO2 (g) are formed with the evolution of 50.33 kJ
of energy.
Substance
∆Hºf (kJ mol -1)
Sº (J mol -1 K -1)
H2O (l)
- 285.8
69.95
CO2 (g)
- 393.5
213.7
O2 (g)
0.0
205.0
C3H8 (g)
?
270.2
Calculate the molar enthalpy of combustion, ∆Hºcomb , of propane
and the standard molar enthalpy of formation, ∆Hºf , of propane
gas.

Consider the Combustion of Propane (C3H8)by O2 and H2o.
C3H8
+5O2 --> 3Co2+ 4H2o
D) At standard temperature and pressure, what
volume of oxygen would be required to burn 100 g of propane? If air
is 21 percent oxygen, what volume of air at STP would be
required?
E) At standard temperature and pressure, what volume of Co2
would be produced when 100g of propane are burned?

18. Butane gas burns according to the following exothermic
reaction:
C4H10 (g) + 13/2 O2 (g) → 4 CO2 (g) + 5 H2O (g) ∆H°rxn = -
2877.1 kJ
a) If 25.0 g of butane were burned, how much energy would be
released?
b) If the reaction of 25.0 g of butane produced a volume change
of 15.4 L against an external pressure of 748 mmHg, calculate the
work done (in J).
c) Calculate the change in internal energy (∆E)...

Consider the balanced equation for the combustion of propane,
C3H8 C3H8(g) + 5O2(g) 3CO2(g) + 4H2O(l) If propane reacts with
oxygen as above a. what is the limiting reagent in a mixture
containing 5.00 g of C3H8 and 10.0 g of O2? b. what mass of the
excess reagent remains after the reaction ? c. what mass of CO2 is
formed when 1.00 g of C3H8 reacts completely?

Calculate the deltaH rxn for the production of CO2 and H20 via
propane combustion, using thermochemical equations below. Show all
work! 3 C (s) + 4 H2 (g) = C3H8 (g) Delta H = (-) 103.9 kJ/mol C
(s) + O2 (g) = CO2 (g) Delta H = (-) 393.5 kJ/mol H2 (g) + 1/2 O2
(g) = H2O (g) Delta H = (-)241. 8 kJ/mol Delta H rxn : ?

Propane (C3H8) burns in oxygen to form carbon dioxide and water.
A 0.5000 g sample of propane was burned in a bomb calorimeter whose
total heat capacity is 17.15 kJ/K. The temperature of the
calorimeter apparatus increased by 2.591 K. Calculate the heat of
combustion per mole of propane.

Butane, the fuel used in cigarette lighters, burns according to
the equation: 2 C4H10 (g) + 13 O2 (g) 8 CO2 (g) + 10 H2O(g) H =
– 5316 kJ a) Calculate the mass of oxygen that must react in order
for this reaction to generate 2150 kJ of heat b) Calculate the
amount of heat, including sign, that is transferred when 75.0 g of
butane react completely.

In a laboratory experiment 24.239 g of methane is burned in air
containing O2 to form gaseous CO2 and H2O. Calculate the final
temperature in °C of the product mixture if the methane and air are
both at an initial temperature of 1.3°C. Assume a stoichiometric
ratio of methane to oxygen from the air, with air being 21% O2 by
volume and the rest of the volume being N2 (c of CO2 = 57.2 J/molK;
c of H2O(g) = 36.0...

Consider C3H8 (g) + 5 O2 (g) à
3 CO2 (g) + 4 H2O (l), with the reaction
being at equilibrium. ∆Ho = -2220 kJ.
What effect will increasing the temperature have on the system?

19.4 g of butane (58.12 g/mol) undergoes combustion according to
the following equation. What pressure of carbon dioxide in atm is
produced at 309 K in a 1.15 L flask.
2 C4H10(g) + 13 O2 (g) → 8
CO2 (g) + 10 H2O (g)

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