Question

Given the following reactions and their enthalpies:

ΔH(kJ/mol)−−−−−−−−−−−

H2(g)⟶2H(g) +436

O2(g)⟶2O(g) +495

H2+1/2O2(g)⟶H2O(g) −242

A. Devise a way to calculate ΔH for the reaction

H2O(g)⟶2H(g)+O(g)

B. estimate the H-O bond energy

Answer #1

The reaction is

H2O(g)⟶2H(g)+O(g)

Given:

H2(g)⟶2H(g) +436
...................................(1)

O2(g)⟶2O(g)
+495....................................(2)

H2+1/2O2(g)⟶H2O(g) −242........................(3)

H2O(g)⟶2H(g)+O(g) ...................................(4)

A) We can derive the given equation from equation 1,2 and 3 as

equation 4 = - equation (3) + equation (1) + 1/2 equation (2)

(Delta H )4 = DeltaH (1) + 1/2 Delta H (2) - Delta H (3)

Delat H rxn = 436 + 495 /2 - (-242) = 925.5 KJ / mole

B) Bond energy and enthalpy of reactin are related as

Delat H rxn = Sum of bond energies of reactants - sum of bond energies of products

For reaction (3)

Delta h rxn = [B.E (H-H)] + 1/2[B.E. O=O] - [2XB.E O-H]

B.E H-H = 436

B.E O=O = 495

-242 = 436 + (495/2) - 2X B.EO-H

Bond energy O-H = 462.75 KJ / mole

+ (

Given the following reactions and their enthalpies:
ΔH(kJ/mol)−−−−−−−−−−− H2(g)⟶2H(g) +436 O2(g)⟶2O(g) +495
H2+12O2(g)⟶H2O(g) −242 Part A Devise a way to calculate ΔH for the
reaction H2O(g)⟶2H(g)+O(g)

Given the following data:
H2(g) + 1/2O2(g) → H2O(l)
ΔH° = -286.0 kJ
C(s) + O2(g) → CO2(g)
ΔH° = -394.0 kJ
2CO2(g) + H2O(l) →
C2H2(g) + 5/2O2(g)
ΔH° = 1300.0 kJ
Calculate ΔH° for the reaction:
2C(s) + H2(g) → C2H2(g)

Calculate the enthalpy of the reaction 2NO(g)+O2(g)→2NO2(g)
given the following reactions and enthalpies of formation:
12N2(g)+O2(g)→NO2(g), ΔH∘A=33.2 kJ
12N2(g)+12O2(g)→NO(g), ΔH∘B=90.2 kJ

1.Using the enthalpies of formation given below, calculate
ΔH°rxn in kJ, for the following reaction.
Report your answer to two decimal places in standard
notation.
H2S(g) + 2O2(g) → SO3(g) +
H2O(l)
H2S (g): -20.60 kJ/mol
O2 (g): 0.00 kJ/mol
SO3 (g): -395.77 kJ/mol
H2O (l): -285.83 kJ/mol
2. Calculate the amount of heat absorbed/released (in kJ) when
22.54 grams of SO3 are produced via the above
reaction.
Report your answer to two decimal places, and use appropriate signs
to...

Hess's Law Given the following data: 2C(s) + 2H2(g) + O2(g) →
CH3OCHO(l) ΔH°=-366.0 kJ CH3OH(l) + O2(g) → HCOOH(l) + H2O(l)
ΔH°=-473.0 kJ C(s) + 2H2(g) + 1/2O2(g) → CH3OH(l) ΔH°=-238.0 kJ
H2(g) + 1/2O2(g) → H2O(l) ΔH°=-286.0 kJ calculate ΔH° for the
reaction: HCOOH(l) + CH3OH(l) → CH3OCHO(l) + H2O(l)

Given the following information:
2 H2 (g) + O2 (g) → 2
H2O (g)
ΔH = −438.6 kJ
3 O2 (g) → 2 O3 (g)
ΔH = +284.6 kJ
Which is a true statement about the reaction below?
3 H2 (g) + O3 (g) → 3
H2O (g)
A) The reaction is exothermic.
B) The reaction will not proceed as written.
C) Multiplying both sides of the reaction by a factor of 2 will
have no effect on the value...

Given the following data:
HNO3(l) → 1/2N2(g) + 3/2O2(g)
+ 1/2H2(g)
ΔH° = 174.1 kJ
2N2(g) + 5O2(g) →
2N2O5(g)
ΔH° = 28.4 kJ
H2(g) + 1/2O2(g) → H2O(l)
ΔH° = -285.8 kJ
Calculate ΔH° for the reaction:
2HNO3(l) → N2O5(g) +
H2O(l)
Note that you should be able to answer this one without
needing to use any additional information from the thermo
table.

You are given the following data:
H2(g) --> 2H(g) Delta H degrees=436.4 kJ/mol
Br2(g) --> 2Br(g) Delta H degrees=192.5 kJ/mol
H2(g) + Br2(g) --> 2HBr(g) Delta H
degrees=-72.4 kJ/mol
Calculate Delta H degrees for the reaction
H(g) + Br(g) --> HBr(g)

Burning H2 (g) in the presence of O2 (g) proceeds by the
following reaction:
H2 (g) + ½ O2 (g) --> H2O (g)
eq. 1
In a fuel cell, the oxidation half-reaction occurring at the
anode (a solid conductor) is:
H2 (g) --> 2H+ (aq) + 2e- eq. 2
At the cathode (solid conductor), O2 is reduced:
O2 (g) + 4H+ (aq) + 4e- --> 2H2O (l) eq. 3
Using Hess’s Law, estimate the heat released by oxidizing...

Given the following thermochemical data:
½H2(g)+AgNO3(aq) → Ag(s)+HNO3(aq) ΔH = -105.0 kJ
2AgNO3(aq)+H2O(l) → 2HNO3(aq)+Ag2O(s) ΔH = 44.8 kJ
H2O(l) → H2(g)+½O2(g) ΔH = 285.8 kJ
Use Hess’s Law to determine ΔH for the reaction:
Ag2O(s) → 2Ag(s)+½O2(g)

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