In a calorimetric experiment 2.50 g of a fuel is burnt in oxygen. 30 % of the energy released during the combustion is absorbed by 500 g of water, the temperature of which rises from 25 °C to 68 °C.
The specific heat capacity of water is 4.2 J g–1 K–1.
What is the total energy released per gram of fuel burnt?
Question 2
Marks: 1
The reaction of hydrochloric acid with sodium hydroxide produced an overall temperature increase of 24.4 K.
Given the following data, how much thermal energy was evolved during this reaction?
Initial temperature of 25.0 cm3 hydrochloric acid = 17.6 oC
Initial temperature of 25.0 cm3 sodium hydroxide = 18.5 oC
The specific heat capacity of water is 4.18 J g-1 K-1.
(25.0 x 4.18 x 6.8) + (25.0 x 4.18 x 5.9)
50.0 x 4.18 x
(50.0 x 4.18 x 6.8) + (50.0 x 4.18 x 5.9)
Question 3
Marks: 1
The temperature rise when 0.1 MJ of heat energy is absorbed by 2.5 kg of solid aluminium is 44.4 oC.
What is the specific heat capacity of aluminium, in J g-1 K-1?
Question 4
Marks: 1
An iron cube, with a mass of 0.5 kg, increases in temperature by 12.7 K when heated.
The specific heat capacity of iron is 0.448 J K-1 g-1.
What is the enthalpy change, in kJ mol-1, for heating the iron cube?
0.448 x 12.7 x 55.85
Question 5
Marks: 1
When completing experiments to measure enthalpy change for exothermic processes, which of the following is not a reason for the experimental data to be lower than the expected value?
Heat loss through convection
Water vapour released as a product
An inadequate supply of oxygen during combustion
Heat transfer to the system
Question 6
Marks: 1
Heptathiepane, S7, can undergo complete combustion to form sulfur dioxide.
S7 (s) + 7O2 (g) → 7SO2 (g)
Which enthalpy changes can be used to describe this reaction?
ΔHfθ
ΔHcθ
ΔHr
A
✔
x
✔
B
x
✔
✔
C
x
✔
x
D
x
x
✔
Question 7
Marks: 1
A student obtained the following experimental results for the enthalpy of combustion of cyclohexane (C6H12).
Mass of water / g
50.00
Initial temperature of the water / °C
19.60
Initial mass of spirit burner and cyclohexane / g
186.79
Final mass of spirit burner and cyclohexane / g
186.29
The student determined from this experiment that the enthalpy of combustion of cyclohexane is –1216 kJ mol–1
The specific heat capacity of water = 4.18 J g–1 K–1 The relative molecular mass (Mr) of cyclohexane = 84.18
Which calculation will correctly determine the final temperature of the water in this experiment?
19.60 +
19.60 +
19.60 +
19.60 +
Question 8
Marks: 1
The diagrams below show a simple calorimeter that is commonly used in the school laboratory and the more accurate chamber calorimeter.
Simple calorimeter
Chamber calorimeter
Which of the following statements correctly explain why the chamber calorimeter is more accurate?
There is less heat loss
There is more complete combustion
There is less fuel lost
I and II only
I and III only
II and III only
I, II and III
Question 9
Marks: 1
Which of the following assumptions are correct when completing the calorimetry experiment and subsequent calculations for the neutralisation of 25.0 cm3 sulfuric acid by 25.0 cm3 barium hydroxide?
That both solutions have the same initial temperature
The value of m in q = mcΔT is 50 g
Heat is lost to the surroundings
I and II only
I and III only
II and III only
I, II and III
Question 10
Marks: 1
The heat produced by the combustion of magnesium is used to heat some water.
Which values are needed to calculate the energy transferred during the reaction?