Question

Using Hess’ Law, compare the heat of combustion of one liter of ethanol with the heat of combustion of one liter of octane. The density of ethanol is 0.789 g/mL and that of octane is 0.703 g/mL.

how do you calculate the number -343.909 kj for CO2 or -241.101 of H2O.. or 200.447kj/mol for C2H4OH?

thank you!

Answer #1

Question 4
Part A
Using the following equation for the combustion of octane,
calculate the heat of reaction for 100.0 g of octane. The molar
mass of octane is 114.33 g/mole.
2 C8H18 + 25 O2 → 16
CO2 + 18 H2O ΔH°rxn = -11018
kJ
Using the following equation for the combustion of octane,
calculate the heat of reaction for 100.0 g of octane. The molar
mass of octane is 114.33 g/mole.
2 C8H18 + 25 O2 → 16...

How much heat (kJ) is released by the complete combustion of
15.0 gallons of octane? This is about the same size as a car's gas
tank. The density of octane is 0.703 g/mL.

Hess's Law
Show how to calculate the standard enthalpy of formation
(ΔHof) of ethanol
C2H5OH(l) from the heat of combustion of
ethanol, which is -1368 kJ/mole, by using tabulated standard
enthalpies of formation for CO2(g) and
H2O(l).
ΔHof(C2H5OH,l) =
________ ? ______

Using the following equation for the combustion of octane,
calculate the heat of reaction for 100.0 g of octane. The molar
mass of octane is 114.33 g/mole.
2 C8H18 + 25 O2 -> 16 CO2 + 18 H2O ,deltaH°rxn =
-11018 kJ
I got- 4820kJ but the answer is 4820kJ.
why is the answer positive when the delta h is negative?

A 12.8 g sample of ethanol (C2H5OH) is
burned in a bomb calorimeter with a heat capacity of 5.65
kJ/°C. The temperature of the calorimeter and the contents
increases from 25°C to 35°C. What is the heat of
combustion per mole of ethanol? The molar mass of ethanol is 46.07
g/mol.
C2H5OH (l) + 3 O2 (g) -----> 2 CO2 (g) + 3
H2O (g) ΔE = ?

11. Using the following equation for the combustion of octane,
calculate the amount of grams of carbon dioxide formed from 100.0 g
of octane. C8H18 + O2 → CO2 + H2O ΔH°rxn = -11018 kJ

The combustion of methane, CH4, releases 890.4 kj/mol of heat.
That is, when one mole of methane is burned, 890.4 kj are give off
to the surroundings. This means that the products have less energy
stored in the bonds than the reactants. Thus, for the reaction:
CH4(G) + 2 O (g) -> CO2 (g) + 2 H2O (I) deltaH= -890.4kj/mol. A)
what is the enthalpy change when 2.00 mol of CH4 are burned? B)what
is the enthalpy change when 22.4g...

Using the following thermal chemical data (use Hess’s law)
2Fe(s) + 6HF(g) —> 2FeF3(s) + 3H2(g)
?rH•= -1787.4 kJ/mol
2Fe(s) + 6HCl(g) —> 2FeCl3(s) + 3H2(g)
?rH•= -1457.0 kJ/mol
calculate?rH• for the following reaction:
FeCl3(s) + 3HF(g) —> FeF3(s) + 3HCl(g)
2. when 19.86g NaOH is dissolved in 125 mL of water in the
coffee-cup calorimeter, the temperature rises from 23•C to 65•C.
what is the enthalpy change per mole of the hydroxide dissolved in
the water? Assume that...

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 : ?

Using Hess's Law and some or all of the equations (1) - (4)
below calculate ΔH at 25C for coal gasification: 2 C(coal) + 2
H2O(g) CH4(g) + CO2(g) ΔH = ? 1. CO(g) + H2(g) C(coal) +
H2O(g) ΔH = −131 kJ/mol 2. C(graphite) + 2 H2(g) CH4(g) ΔH =
−74.8 kJ/mol 3. CO(g) + 3 H2(g) CH4(g) + H2O(g) ΔH = −206 kJ/mol
4. CO(g) + H2O(g) CO2(g) + H2(g) ΔH = −41...

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