Question

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 C_{8}H_{18} + 25 O_{2} → 16
CO_{2} + 18 H_{2}O 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 C_{8}H_{18} + 25 O_{2} → 16
CO_{2} + 18 H_{2}O ΔH°_{rxn} = -11018
kJ

-4.82 x 10^{3} kJ |

-9.64 x 10^{3} kJ |

-1.26 x 10^{4} kJ |

-4.82 kJ |

Answer #1

**answer** : **ΔH°rxn = - 4.82 x 10^3
kJ**

2 C_{8}H_{18} + 25 O_{2}
---------------> 16 CO_{2} + 18
H_{2}O
ΔH°_{rxn} = -11018 kJ

moles of octane = 100 / 114.33 = 0.875 mol

2 mol octane --------------->
ΔH°_{rxn} = -11018 kJ

0.875 mol octane ------------------> ??

ΔH°_{rxn } = 0.875 x - 11018 /
2

**ΔH°rxn = - 4.82 x 10^3 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 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?

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

Calculate heat of combustion reaction of 1.0 g of octane:
2 C8H18 + 25 O2 --> 16 CO2 + 18 H2O
The calorimeter contains 1200 g water, and the temperature
changes from 25.00 deg C to 33.20 deg C. Heat capacity of bomb is
837 J/deg C.

Octane (C8H18) undergoes combustion according to the following
thermochemical equation:
2C8H18(l) + 25O2(g) 16CO2(g) +
18H2O(l) ∆H°rxn = −10,800
kJ/mol
Given that ∆H°f[CO2(g)] = −394 kJ/mol and ∆H°f[H2O(l)] = −286
kJ/mol, calculate the standard enthalpy of formation of
octane.
a. −326 kJ/mol
b.326 kJ/mol
c.210 kJ/mol
d.-218 kJ/mol

Balance the chemical equation a×C8H18 + b×O2 》c×CO2 +
d×H2O for the combustion reaction of octane by determining the
numbers a,b,c, and d

9. Use the following experimentally derived combustion
data to calculate the standard molar enthalpy of formation
(ΔH°f ) of liquid methanol (CH3OH) from its
elements.
2 CH3OH(l) + 3 O2(g) → 2
CO2(g) + 4 H2O(l)
ΔH°rxn = −1452.8 kJ
C(graphite) + O2(g) →
CO2(g)
ΔH°rxn = −393.5 kJ
2 H2(g) + O2(g) → 2
H2O(l)
ΔH°rxn = −571.6 kJ
(1) −238.7 kJ/mol (2) 487.7
kJ/mol (3) −548.3 kJ/mol
(4) 20.1 kJ/mol
(5) 47.1 kJ/mol

How many kilograms of CO2 would be produced through
combustion of a gallon (2.6 kg) of octane
(C8H18)?
2 C8H18 (g) + 25 O2 (g) -->
16 CO2 (g) + 18 H2O (g)

Part A
Determine the mass of CO2 produced by burning enough of methane
to produce 2.25×102kJ of heat.
CH4(g)+2O2(g)→CO2(g)+2H2O(g)ΔH∘rxn=−802.3kJ
Express your answer using three significant figures.
Part B
Determine the mass of CO2 produced by burning enough of propane
to produce 2.25×102kJ of heat.
C3H8(g)+5O2(g)→3CO2(g)+4H2O(g)ΔH∘rxn=−2217kJ
Express your answer using three significant figures.
Part C
Determine the mass of CO2 produced by burning enough of octane
to produce 2.25×102kJ of heat.
C8H18(l)+25/2O2(g)→8CO2(g)+9H2O(g)ΔH∘rxn=−5074.1kJ
Express your answer using three significant figures.
Part D...

The standard heat of formation, ΔH∘f, is defined as the enthalpy
change for the formation of one mole of substance from its
constituent elements in their standard states. Thus, elements in
their standard states have ΔH∘f=0. Heat of formation values can be
used to calculate the enthalpy change of any reaction.
Consider, for example, the reaction
2NO(g)+O2(g)⇌2NO2(g)
with heat of formation values given by the following table:
Substance ΔH∘f
(kJ/mol)
NO(g) 90.2
O2(g) 0
NO2(g) 33.2
Then the standard heat...

The thermochemical equation for the combustion of one mole of
carbon monoxide is as follows: CO(g) + ½ O2 → CO2(g) ΔH = −283 kJ
Calculate the heat change for the decomposition of 2.00 lb carbon
dioxide gas into CO and oxygen.

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