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WorksheetsThermochemistry
Total questions: 15
Worksheet time: 25mins
In which of the chemical reactions releases heat to the surroundings?
Dissolving potassium nitrate in water
Dissolving ammonium sulphate in water
Adding calcium carbonate to nitric acid
Adding potassium hydrogen carbonate to hydrochloric acid
Which statement is correct about exothermic reaction?
The heat absorbed during bond breaking is more than the heat released during bond formation
The heat absorbed during bond breaking is less than the heat released during bond formation
The heat absorbed during bond breaking is equal to the heat released during bond formation
No heat is absorbed or released during bond breaking and bond formation
The diagram shows the energy profile for the formation of T from R and S.
What is the activation energy for the reaction?
y kJ mol-1
(x + y) kJ mol-1
x kJ mol-1
(x-y) kJ mol-1
The reaction between nitrogen and oxygen can be represented by the following equation:
Which of the following energy level diagrams represent the above reaction?
The following equation shows the reaction between silver nitrate, AgNO3 and sodium chloride, NaCl.
Which of the following shows that the reaction is an exothermic reaction?
Silver chloride precipitate is formed in the reaction
The reaction needs 65.5 kJ of heat energy to form 1 mol of silver chloride
The total energy absorbed to break the bonds is more than the total energy released during the precipitation of silver chloride.
The energy contained in silver nitrate and sodium chloride is higher than the energy contained in silver chloride and sodium nitrate.
An experiment was carried out to determine the heat of precipitation for the reaction between silver nitrate and sodium chloride. Table 5 shows the temperature reading of both solutions.
Based on Table 5, which of the following is true?
[Specific heat capacity: 4.0 J g-1 °C-1; Relative atomic mass: Ag=108; Cl=35.5]
CHOOSE MORE THAN 1 ANSWER!
7.2 g white precipitate is formed.
Heat released during the experiment is 2000 J
The amount of silver nitrate used is 0.05 mol
Heat released during the formation of bonds is more than heat absorbed during the breaking of bonds.
In an experiment 2.4 g of magnesium powder is added to 100 cm3 of 2.0 mol dm-3 copper(II) sulphate solution. The temperature of the mixture increases by 1.0 °C. What is the heat of reaction in the experiment?
[Specific heat capacity of a solution = 4.2 J g-1 0C-1; Relative atomic mass of Mg=24]
- 0.42 kJ mol-1
- 0.48 kJ mol-1
- 4.20 kJ mol-1
- 4.80 kJ mol-1
Which of the following acids, when added to 50 cm3 of 0.01 mol dm-3 sodium hydroxide solution, produce the same rise in temperature of the mixture?
50 cm3 of 0.01 mol dm-3 hydrochloric acid
25 cm3 of 0.01 mol dm-3 sulphuric acid
50 cm3 of 0.01 mol dm-3 nitric acid
50 cm3 of 0.01 mol dm-3 ethanoic acid
When 50 cm3 of 1.0 moldm-3 nitric acid is mixed with 50 cm3 of 1.0 moldm-3 sodium hydroxide solution the temperature increases by 6.0 °C. What is the temperature change if the experiment is repeated using 50 cm3 of 2.0 mol dm-3 nitric acid with 50 cm3 of 1.0 mol dm-3 sodium hydroxide?
3.0 °C
6.0 °C
9.0 °C
12.0 °C
Below are two thermo chemical equations for the neutralization process.
NaOH + HCl -- > NaCl + H2O ; ΔH = -57 kJ mol-1
NaOH + CH3COOH -- > CH3COONa + H2O ; ΔH = -55 kJ mol-1
The value of the heat of neutralization for both processes are different because …..
the ethanoic acid is less soluble in water.
the production of sodium ethanoate salt absorbs heat.
the ethanoic acid produces only a small amount of hydrogen ions.
greater amount of heat is absorbed to ionize the ethanoic acid molecule.
When 100 cm3 of 1.0 mol dm-3 of sodium hydroxide is added to 100 cm3 of 1.0 mol dm-3 of hydrochloric acid, temperature rises by 7 °C. Which of the following mixtures will produce an increment of 14 °C in temperature?
50 cm3 of 1.0 mol dm-3 of sodium hydroxide 50 cm3 of 1.0 mol dm-3 of hydrochloric acid
50 cm3 of 2.0 mol dm-3 of sodium hydroxide and 50 cm3 of 2.0 mol dm-3 of hydrochloric acid
100 cm3 of 1.0 mol dm-3 of sodium hydroxide and 100 cm3 of 4.0 mol dm-3 hydrochloric acid
200 cm3 of 1.0 mol dm-3 sodium hydroxide and 200 cm3 of 1.0 mol dm-3 hydrochloric acid
When 100 cm3 of 1.0 mol dm-3 hydrochloric acid reacts with 100 cm3 of 1.0 mol dm-3 potassium hydrogen carbonate solution the temperature decreased by y °C . What is the decrease in temperature for the reaction when 50 cm3 of 1.0 mol dm-3 hydrochloric acid reacts with 50 cm3 of 1.0 mol dm-3 potassium hydrogen carbonate solution ?
0.1 y °C
0.5 y °C
y °C
2 y °C
The following thermochemical equation shows a combustion reaction between hexane. C6H14 and oxygen.
What is the mass of hexane need to be burnt to produce heat that can heat up 2 kg of water from 25 °C to 100°C?
[Relative atomic mass : C=12, H=l; specific heat capacity of water = 4.2 Jg-1 °C-1]
5.16 g
5.56 g
15.48 g
16.67 g
The table shows the heat of combustion of three alcohols.
Which of the following factors increases the heat of combustion of alcohols?
size of molecules decreases
number of carbon atoms per molecule increases
number of oxygen atoms per molecule increases
number of hydrogen atoms per molecule decreases
Diagram 15 shows the set-up of apparatus to determine heat of combustion of ethanol.
The heat of combustion of ethanol was found less than the theoretical value. What can be done to improve the experimental value?
Remove the wooden block
Use copper container to replace beaker
Do not use wire gauze when heating
Use greater volume of water
