CHEMISTRY DEPARTMENT
WAID ACADEMY
ENTHALPY
The enthalpy of combustion of methanol,
CH3OH, is -715 kJ mol-1.
The mass of methanol which has to be
burned to produce 71.5 kJ is
25
1.
2.
3.
4.
3.2 g
32g
71.5 g
715 g
0%
3.2 g
32g
71.5 g
715 g
A group of students added 6 g of ammonium chloride crystals to
200 cm3 of water at a temperature of 25oC.
The enthalpy of solution of ammonium chloride is +13.6 kJ mol-1.
After dissolving the crystals, the temperature of the solution would
most likely be
1.
2.
3.
4.
20
30oC.
27oC.
25oC.
23oC.
0%
30oC.
27oC.
25oC.
23oC.
Which equation illustrates an
enthalpy of combustion?
25
1. A.
0%
2. B.
3. C.
4. D.
A.
B.
C.
D.
When 3.6 g of butanal (relative formula mass = 72)
was burned, 134 kJ of energy was released.
From this result, what is the enthalpy of combustion,
in kJ mol-1?
20
1.
2.
3.
4.
-6.7
+6.7
-2680
+2680
0%
-6.7
6.7
-2680
2680
The enthalpy of neutralisation in an acid/alkali
reaction is always the energy released in
20
1. the neutralisation of
one mole of acid.
2. the neutralisation of
mole of alkali.
3. the formation of one
mole of salt.
4. the formation of one
mole of water.
0%
the neutralisation of one mole of acid.
the neutralisation of mole of alkali.
the formation of one mole of salt.
A potential energy diagram for a reaction is shown
below.
20
The enthalpy change for the reaction is
1.
2.
3.
4.
-361 kJ
-227 kJ
-91kJ
+361kJ
0%
-361 kJ
-227 kJ
-91kJ
+361kJ
Which set of data refer to the diagram shown
below?
25
1.
Enthalpy change = - 60 kJ
A
Activation energy = - 80 kJ
2.
Enthalpy change = +80 kJ
B
Activation energy = - 60 kJ
3.
Enthalpy change = +60 kJ
C
Activation energy = +80 kJ
4.
Enthalpy
change = -60 kJ
D
Activation energy = +80 kJ
0%
A
B
C
D
The enthalpy change for the
forward reaction shown in
the diagram opposite can be
represented by
20
1.
2.
3.
4.
x
y
x+y
x-y
0%
x
y
x+y
x-y
When 0.1 g of an alcohol is burned the energy released
increased the temperature of 200cm3of water from 23.1 oC
to 34.2oC.
Calculate the enthalpy change for this reaction in kJ mol-1.
20
1.
2.
3.
4.
0%
+ 4.64 kJ
- 4.64 kJ
- 9.28 kJ
+ 9.28 kJ
+ 4.64 kJ
- 4.64 kJ
- 9.28 kJ
+ 9.28 kJ
When 0.01 mole of compound X is burned the energy
given out raised the temperature of 250cm3 of water by
22.4oC.
Calculate the enthalpy of combustion of compound X,
in kJ mol-1.
20
1.
2.
3.
4.
- 0.936
- 23.408
- 234.08
- 2340.8
0%
-0.936
-23.408
-234.08
-2340.8