STRAIGHTERLINE CHEMISTRY EXAM SCRIPT
BUNDLE 2026 COMPLETE QUESTIONS AND
SOLUTIONS GRADED A+
◉ Given the thermochemical equation:
2SO2 + O2 2SO3 ΔHorxn = ─198 kJ.
What is the enthalpy change (ΔHo) for the decomposition of one
mole of SO3?
A. 198 kJ B. ─99 kJ C. 99 kJ D. 396 kJ E. ─198 kJ. Answer: C
◉ Given:
H2(g) + 1/2O2(g) H2O(l) ΔHof = ─286 kJ
What is the enthalpy change for the following reaction?
2H2O(l) 2H2(g) + O2(g) ΔHorxn = ?
A. ΔHo = ─286 kJ
B. ΔHo = +286 kJ
C. ΔHo = ─572 kJ
D. ΔHo = +572 kJ
E. ΔHo = ─143 kJ. Answer: D
◉ A home aquarium is an example of an open system. Answer: TRUE
,◉ In an endothermic process heat is absorbed by the system..
Answer: TRUE
◉ The heat absorbed by a system at constant pressure is equal to ΔE
+ PΔV.. Answer: TRUE
◉ The work done on the surroundings by the expansion of a gas is w
= ─PΔV.. Answer: TRUE
◉ The heat capacity of 20.0 g of water is 83.7 J/oC.. Answer: TRUE
◉ If 2Mg(s) + O2(g) 2MgO(s) ΔHo = ─1203.6 kJ; then for Mg(s) +
1/2O2(g) MgO(s)
the enthalpy change is ΔHf = ─601.8 kJ. Answer: TRUE
◉ Chemical reactions in a bomb calorimeter occur at constant
pressure
Conditions.. Answer: FALSE
◉ The specific heats of water and iron are 4.184 and 0.444 J/g•oC,
respectively.
,When equal masses of water and iron both absorb the same amount
of heat, the temperature increase of the water will be 5.42 times
greater than that of the iron.. Answer: FALSE
◉ Pentaborane B5H9(s) burns vigorously in O2 to give B2O3(s) and
H2O(l). Write and balance the combustion equation. Calculate the
ΔHorxn for the combustion of 1 mol of B5H9 given the following
enthalpies of formation.
ΔHof[B2O3(s)] = ─1273.5 kJ/mol
ΔHof[B5H9(s)] = 73.2 kJ/mol
ΔHof[H2O(l)] = ─285.8 kJ/mol
A. ─1.2735 MJ
B. ─4.543 MJ
C. ─18.170 MJ
D. ─9.086 MJ
E. ─8.448 MJ. Answer: B
◉ For the reaction:
C(s) + O2(g) CO2(g) ΔHof = ─393 kJ
How many grams of C(s) must be burned to release 275 kJ of heat?
A. 22.3 g B. 0.70 g C. 12.0 g D. 17.1 g E. 8.40 g. Answer: E
, ◉ The combustion of butane produces heat according to the
equation:
2C4H10(g) + 13O2(g) 8CO2(g) + 10H2O(l) ΔHorxn = ─5,314 kJ
What is the heat of combustion per gram of butane?
A. -32.5 kJ B. -45.7 kJ C. -91.5 kJ D. -2,656 kJ E. -15,440 kJ. Answer: B
◉ The combustion of octane produces heat according to the
equation:
2C8H18(l) + 25O2(g) 16CO2(g) + 18H2O(l) ΔHorxn= ─11,020 kJ
What is the heat of combustion per gram of octane?
A. 5.510 MJ B. 96.5 kJ C. 48.2 kJ D. 193 kJ E. 629.2 MJ. Answer: C
◉ The combustion of butane produces heat according to the
equation:
2C4H10(g) + 13O2(g) 8CO2(g) + 10H2O(l) ΔHorxn= ─5314 kJ
How many grams of butane must be burned to release 6375 kJ of
heat?
A. 1.20 g B. 139 g C. 0.0413 g D. 69.7 g E. 97.8 g. Answer: B
◉ Given the following information:
CaO(s) + H2O(l) Ca(OH)2(s) ΔHorxn = ─64.8 kJ/mol
How many grams of CaO must react in order to liberate 525 kJ of
heat?
BUNDLE 2026 COMPLETE QUESTIONS AND
SOLUTIONS GRADED A+
◉ Given the thermochemical equation:
2SO2 + O2 2SO3 ΔHorxn = ─198 kJ.
What is the enthalpy change (ΔHo) for the decomposition of one
mole of SO3?
A. 198 kJ B. ─99 kJ C. 99 kJ D. 396 kJ E. ─198 kJ. Answer: C
◉ Given:
H2(g) + 1/2O2(g) H2O(l) ΔHof = ─286 kJ
What is the enthalpy change for the following reaction?
2H2O(l) 2H2(g) + O2(g) ΔHorxn = ?
A. ΔHo = ─286 kJ
B. ΔHo = +286 kJ
C. ΔHo = ─572 kJ
D. ΔHo = +572 kJ
E. ΔHo = ─143 kJ. Answer: D
◉ A home aquarium is an example of an open system. Answer: TRUE
,◉ In an endothermic process heat is absorbed by the system..
Answer: TRUE
◉ The heat absorbed by a system at constant pressure is equal to ΔE
+ PΔV.. Answer: TRUE
◉ The work done on the surroundings by the expansion of a gas is w
= ─PΔV.. Answer: TRUE
◉ The heat capacity of 20.0 g of water is 83.7 J/oC.. Answer: TRUE
◉ If 2Mg(s) + O2(g) 2MgO(s) ΔHo = ─1203.6 kJ; then for Mg(s) +
1/2O2(g) MgO(s)
the enthalpy change is ΔHf = ─601.8 kJ. Answer: TRUE
◉ Chemical reactions in a bomb calorimeter occur at constant
pressure
Conditions.. Answer: FALSE
◉ The specific heats of water and iron are 4.184 and 0.444 J/g•oC,
respectively.
,When equal masses of water and iron both absorb the same amount
of heat, the temperature increase of the water will be 5.42 times
greater than that of the iron.. Answer: FALSE
◉ Pentaborane B5H9(s) burns vigorously in O2 to give B2O3(s) and
H2O(l). Write and balance the combustion equation. Calculate the
ΔHorxn for the combustion of 1 mol of B5H9 given the following
enthalpies of formation.
ΔHof[B2O3(s)] = ─1273.5 kJ/mol
ΔHof[B5H9(s)] = 73.2 kJ/mol
ΔHof[H2O(l)] = ─285.8 kJ/mol
A. ─1.2735 MJ
B. ─4.543 MJ
C. ─18.170 MJ
D. ─9.086 MJ
E. ─8.448 MJ. Answer: B
◉ For the reaction:
C(s) + O2(g) CO2(g) ΔHof = ─393 kJ
How many grams of C(s) must be burned to release 275 kJ of heat?
A. 22.3 g B. 0.70 g C. 12.0 g D. 17.1 g E. 8.40 g. Answer: E
, ◉ The combustion of butane produces heat according to the
equation:
2C4H10(g) + 13O2(g) 8CO2(g) + 10H2O(l) ΔHorxn = ─5,314 kJ
What is the heat of combustion per gram of butane?
A. -32.5 kJ B. -45.7 kJ C. -91.5 kJ D. -2,656 kJ E. -15,440 kJ. Answer: B
◉ The combustion of octane produces heat according to the
equation:
2C8H18(l) + 25O2(g) 16CO2(g) + 18H2O(l) ΔHorxn= ─11,020 kJ
What is the heat of combustion per gram of octane?
A. 5.510 MJ B. 96.5 kJ C. 48.2 kJ D. 193 kJ E. 629.2 MJ. Answer: C
◉ The combustion of butane produces heat according to the
equation:
2C4H10(g) + 13O2(g) 8CO2(g) + 10H2O(l) ΔHorxn= ─5314 kJ
How many grams of butane must be burned to release 6375 kJ of
heat?
A. 1.20 g B. 139 g C. 0.0413 g D. 69.7 g E. 97.8 g. Answer: B
◉ Given the following information:
CaO(s) + H2O(l) Ca(OH)2(s) ΔHorxn = ─64.8 kJ/mol
How many grams of CaO must react in order to liberate 525 kJ of
heat?
