Which one of the following reactions occurring at 25oC does the symbol ΔHof[H2SO4(l)] refer
to?
A. 2H(g) + S(g) + 4O(g) H2SO4(l)
B. H2(g) + S(g) + 2O2(g) H2SO4(l)
C. H2SO4(l) H2(g) + S(s) + 2O2(g)
D. H2SO4(l) 2H(g) + S(s) + 4O(g)
E. H2(g) + S(s) + 2O2(g) H2SO4(l) - ANSWER E
Naphthalene combustion can be used to determine the heat capacity of a bomb calorimeter.
The heat of combustion of naphthalene is 40.1 kJ/g. When 0.8210 g of naphthalene was
combusted in a calorimeter containing 1000 g of water a temperature rise of 4.21oC was
observed. What is the heat capacity of the bomb calorimeter excluding the water?
A. 32.9 kJ/oC
B. 7.8 kJ/oC
C. 1.76 kJ/oC
D. 1.76 kJ/oC
E. 15.3 kJ/oC - ANSWER C
Which of the following processes is endothermic?
a. O2(g) + 2H2(g) 2H2O(g)
b. H2O(g) H2O(l)
c. 3O2(g) + 2CH3OH(g) 2CO2(g) + 2H2O(g)
d. H2O(s) H2O(l) - ANSWER D
,A 100 mL sample of 0.200 M aqueous hydrochloric acid is added to 100 mL of 0.200 M aqueous
ammonia in a calorimeter whose heat capacity is 480 J K ─ 1. The following reaction occurs
when the two solutions are mixed.
HCl(aq) + NH3(aq) NH4Cl(aq)
The temperature increase is 2.34oC. Calculate ΔH per mole of HCl neutralized.
A. 154 kJ B. 44.5 kJ C. 22.5 kJ D. ─22.5 kJ E. ─56.2 kJ - ANSWER E
A 0.1326 g sample of magnesium was burned in an oxygen bomb calorimeter. The Htotal heat
capacity of the calorimeter plus water was 5760 J/oC. If the temperature rise of the
calorimeter with water was 0.570oC, calculate the enthalpy of combustion of magnesium.
Mg(s) + 1/2O2(g) MgO(s)
A. ─3280 kJ/mol B. ─24.8 kJ/mol C. 435 kJ/mol
D. 106 kJ/mol E. ─602 kJ/mol - ANSWER E
Which one of the following reactions occurring at 25oC does the symbol ΔHof[H2SO4(l)] refer
to?
A. 2H(g) + S(g) + 4O(g) H2SO4(l)
B. H2(g) + S(g) + 2O2(g) H2SO4(l)
C. H2SO4(l) H2(g) + S(s) + 2O2(g)
D. H2SO4(l) 2H(g) + S(s) + 4O(g)
E. H2(g) + S(s) + 2O2(g) H2SO4(l) - ANSWER E
Which one of the following reactions occurring at 25oC does the symbol ΔHof[HNO3(l)] refer
to?
A. H(g) + N(g) + O3(g) HNO3(l)
B. 1/2H2(g) + 1/2N2(g) + 3/2O2(g) HNO3(l)
C. HNO3(l) 1/2H2(g) + 1/2N2(g) + 3/2O2(g)
D. HNO3(l) H(g) + N(g) + 3O(g)
E. H2(g) + N2(g) + O3(g) HNO3(l) - ANSWER B
,When 0.56 g of Na(s) react with excess F2(g) to form NaF(s) at standard state conditions, 13.8
kJ of heat
are evolved. What is the standard enthalpy of formation (ΔHof) of NaF(s)?
A. 24.8 kJ/mol B. +570 kJ/mol C. ─24.8 kJ/mol D. ─7.8 kJ/mol
E. ─570 kJ/mol - ANSWER E
Ethanol undergoes combustion according to the equation:
C2H5OH(l) + O2(g) CO2(g) + H2O(l) (Not Balanced)
The standard heat of combustion of ethanol, C2H5OH(l), is ─1366.8 kJ/mol. Given that:
ΔHof[CO2(g)] = ─393.5 kJ/mol
ΔHof[H2O(l)] = ─285.8 kJ/mol
What is the standard enthalpy of formation of ethanol?
A. 3010 kJ
B. ─687.6 kJ
C. ─277.6 kJ
D. 687.6 kJ
E. 1367 kJ - ANSWER C
Find the standard enthalpy of formation of ethylene, C2H4(g), given the following data:
C2H4(g) + 3O2(g) 2CO2(g) + 2H2O(l) ΔHof = ─1411 kJ
C(s) + O2(g) CO2(g) ΔHof = ─393.5 kJ
H2(g) + 1/2O2(g) H2O(l) ΔHof = ─285.8 kJ
A. 52 kJ
B. 87 kJ
C. 731 kJ
D. 1.41 103 kJ
, E. 2.77 103 kJ - ANSWER A
Octane (C8H18) undergoes combustion according to the following thermochemical equation:
2C8H18(l) + 25O2(g) 16CO2(g) + 18H2O(l) ΔHorxn = ─11,020 kJ.
Given that: ΔHof[CO2(g)] = ─393.5 kJ/mol
ΔHof[H2O(l)] = ─285.8 kJ/mol
Calculate the enthalpy of formation of 1 mole of octane.
A. ─210 kJ B. ─11,230 kJ C. 22,040 kJ D. ─420 kJ E. 420 kJ - ANSWER A
Glycine C2H5O2N is important for biological energy. The combustion of glycine is given by the
equation,
4C2H5O2N(s) + 9O2(g) 8CO2(g) + 10H2O(l) + 2N2(g) ΔHorxn = ─3857 kJ
Given that ΔHof[CO2(g)] = ─393.5 kJ/mol, and ΔHof[H2O(l)] = ─285.8 kJ/mol. Calculate
the enthalpy of formation ΔHof per mole of glycine.
A. ─537.2 kJ/mol
B. ─268.2 kJ/mol
C. 2149 kJ/mol
D. ─3178 kJ/mol
E. ─964 kJ/mol - ANSWER A
Calculate ΔHorxn for the following reaction.
2H2O2(l) 2H2O(l) + O2(g)
Use the following information:
ΔHof (H2O2(l)) = -187.6 kJ/mol ; ΔHof (H2O(l)) = -285.8 kJ/mol ; ΔHof (O2(g)) = 0
kJ/mol A. 53.0 kJ B. 98.2 kJ C. -98.2 kJ D. 196.4 kJ E. ─196.4 kJ - ANSWER E
Given 2Al(s) + 3/2O2(g) Al2O3(s) ΔHof = ─1670 kJ
What is ΔH for the reaction?
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