WorksheetsThermochemical Reactions
Total questions: 20
Worksheet time: 58mins
ΔH is the same thing as:
temperature
q
m
C
ΔH means:
temperature
calorimetry
enthalpy
syntropy
A positive ΔH means the reaction is:
complete
at equilibrium
exothermic
endothermic
A positive ΔH means that:
In order for the reaction to happen, heat must be input. It is exothermic
In order for the reaction to happen, heat must be input. It is endothermic.
When the reaction happens, heat is released. It is exothermic
When the reaction happens, heat is released. It is endothermic
If ΔH is positive, heat would be shown on the _____ side of the thermochemical equation.
Reactant
Product
Is the following exothermic or endothermic?
Endothermic
Exothermic
Is the following exothermic or endothermic?
Endothermic
Exothermic
Calculate ΔH when 2 moles of ethanol (C2H5OH) reacts with excess oxygen according to the following thermochemical equation?
C2H5OH + 3O2 → 2CO2 + 3H2O ΔH = −1366.7 kJ
-2733.4 kJ
-683.35 kJ
-1366.7 kJ
-910.67 kJ
What will ΔH be if there is 1 mole of oxygen?
4Fe(s) + 3O2(g) --> 2Fe2O3(s) ΔH = –1500 kJ
-500 kJ
500 kJ
-750 kJ
-4500 kJ
What is ΔH if 2 mol of O2(g) is reacted in this reaction?
H2(g) + ½ O2(g) → H2O(l) ∆H = -285.8 kJ
-570 kJ
-71.45 kJ
-1143.2 kJ
-142.9 kJ
What mass of P4 must be reacted to produce 5905 kJ of energy?
P4 + 6Cl2 --> 4PCl3 + 2439 kJ
25.43 g
563.0 g
2.421 g
300.0 g
The enthalpy change for the reaction
C(s, graphite) + 1⁄2O2(g) --> CO(g) cannot be measured directly since some carbon dioxide is always formed in the reaction.
It can be calculated using Hess’s Law and the enthalpy changes of combustion of graphite and of carbon monoxide.
C(s, graphite) + O2(g) --> CO2 ΔH=-394 kJmol–1
CO(g) + 1⁄2O2(g) --> CO2 ΔH=-283 kJmol–1
The enthalpy change for the reaction of graphite with oxygen to give carbon monoxide is
-677 kJmol–1
+111 kJmol–1
-111 kJmol–1
+677 kJmol–1
C(s) + O2(g) -> CO2(g) ∆H=a
H2(g) + ½O2(g) -> H2O(l) ∆H=b
C4H9OH(l) + 6O2(g) -> 4CO2(g) + 5H2O(l) ∆H=c
What is the enthalpy change for the reaction shown below?
4C(g) + 5H2(l) + ½O2(g) -> C4H9OH(l)
The standard enthalpy changes of combustion of carbon, hydrogen and methane are shown in the table.
Which one of the following expressions gives the correct value for the standard enthalpy change of formation of methane in kJ mol–1?
C(s) + 2H2(g) → CH4(g)
394 + (2 × 286) – 891
–394 – (2 × 286) + 891
394 + 286 – 891
–394 – 286 + 891
2N2 + 3H2 --> 2NH3 + 46 kJ
How much energy would be produced if only 1 mol of nitrogen was reacted?
ΔH○f [Fe2O3(s)] = –820 kJ mol–1
Select the expression which gives the enthalpy change, in kJ mol–1, for the reaction:
2FeO(s) + 1⁄2O2(g) → Fe2O3(s)
What is the enthalpy change under standard conditions for the following reaction?
3FeO(s) + 2Al (s) -> 3Fe(s) + Al2O3(s)
Which statement about this information is correct?
than the total energy of the bonds
formed in the product
