Answer All Questions.
1. The diagram shows the temperature change for a mixture during an exothermic reaction.
An exothermic reaction is a chemical reaction that
A releases heat energy to the surroundings.
B neither absorbs nor releases heat energy.
C absorbs heat energy from the surroundings.
2. What is the name of the diagram?
A Energy level diagram
B Energy change diagram
C Reactant-product diagram
D Chemical reaction diagram
3. In the thermochemical equation, ∆H is the heat of precipitation of silver chloride.
Ag+(aq) + Cl-(aq) à AgCl(s) ∆H = -65 kJ mol-1
Based on the equation, the heat of precipitation of silver chloride is the energy change when
A silver chloride is formed from its ions.
B silver chloride ionizes in water to form its ions.
C 1 mole of silver chloride is formed from its ions.
D 1 mole of silver chloride ionizes in water to form its ions.
4. In the thermochemical equation, ∆H is the heat of displacement of metal M.
M2+(aq) + N (s) à M (s) + N2+(aq) ∆H = -200 kJ mol-1
Based on the equation, heat of displacement of metal M is the energy change when
A 1 mole of metal M is displaced from its salt solution by a less electropositive metal.
B 1 mole of metal M is displaced from its salt solution by a more electropositive metal.
C 1 mole of metal M is formed when its oxide is reduced by a more electropositive metal.
D 1 mole of metal M is formed when its oxide is reduced by a less electropositive metal.
5. The thermochemical equation for the reaction between hydrochloric acid, HCl and sodium hydroxide solution, NaOH is shown below.
HCl(aq) + NaOH (aq) à NaCl (aq) + H2O (l) ∆H = -57.3 kJ mol-1
Based on the equation, ∆H is the
A heat of combustion
B heat of precipitation
C heat of displacement
D heat of neutralization
6. When methane, CH4 is burnt, heat is given out as shown in the thermochemical equation.
∆H in the equation represents
A heat of combustion
B heat of precipitation
C heat of displacement
D heat of neutralization
7. In cold packs, solid ammonium sulphate dissolves in water to produce an endothermic reaction.
Which of the following is true about endothermic reaction?
A Temperature remains.
B Temperature increases.
C Heat energy is released to the surroundings.
D Heat energy is absorbed from the surroundings.
8. Heat change during an experiment can be calculated using the formula shown below:
Heat change, H = mcθ
What is represented by θ in the formula?
A Initial temperature
B Lowest temperature
C Highest temperature
D Temperature change
9. Which of the following chemical reaction is a endothermic reaction?
A Respiration
B Combustion
C Neutralization
D Photosynthesis
10. The thermochemical equation for the combustion of sulphur is shown below.
S(s) + O2(g) à SO2(g) ∆H = -292 kJ mol-1
The negative symbol of the heat of combustion shows that
| | Heat energy | The reaction mixture temperature |
| A | released | increases |
| B | released | decreases |
| C | absorbed | increases |
| D | absorbed | decreases |
11. The thermochemical equation for a neutralization reaction is given below.
HCl (aq) + KOH (aq) à KCl (aq) + H2O(l) ∆H = -57 kJ mol-1
Which of the following statements is true about ∆H?
A 1 mole of water contains 57 kJ of energy.
B 1 mole of water contains -57 kJ of energy.
C Formation of 1 mole of water absorbs 57 kJ of energy.
D Formation of 1 mole of water releases 57 kJ of energy.
12. Which of the following is not required when determining the energy change of a chemical reaction?
A The change in temperature.
B The time needed to complete the reaction.
C The mass of the aqueous reaction mixture.
D The specific heat capacity of the aqueous reaction mixture.
13. Which of the following physical processes releases energy to the surroundings?
A Boiling
B Melting
C Evaporation
D Condensation
14. Which of the following alcohols has the lowest heat of combustion?
A C2H5OH
B C3H7OH
C C4H9OH
D C5H11OH
15. The figure shows the energy level diagram of a chemical reaction.
Which of the following statement is true?
A The reaction is exothermic.
B The heat of reaction, ∆H is positive.
C Heat energy is released in the reaction.
D The energy content of the reactants is more than the products.
16. The table below shows the results of a series of experiments carried out by a student.
| Experiment | Initial temperature (oC ) | Highest / lowest temperature of the mixture (oC ) |
| I | 28.0 | 30.5 |
| II | 28.0 | 27.5 |
| III | 27.0 | 30.0 |
| IV | 27.0 | 25.0 |
Which of the following experiments are endothermic reactions?
A I and II
B I and III
C II and IV
D III and IV
17. The thermochemical equation for the reaction between hydrogen and oxygen is shown below:
H2(g) + ½ O2(g) à H2O(l) ∆H = - 287 kJ mol-1
Based on the equation, which of the following is true?
A The reaction is endothermic
B Heat energy is absorbed to form water
C Heat energy is released during the reaction.
D Heat energy is released when H-H and O-O bonds are broken.
18. Hydrogen and chlorine react to form hydrogen chloride as shown by the equation.
H2(g) + Cl2(g) à 2HCl(g)
Which of the following requires energy?
A Breaking of bonds in hydrogen and chlorine molecules.
B Formation of bonds between chlorine atoms and hydrogen ions.
C Breaking of bonds in hydrogen molecules to form hydrogen ions.
D Formation of bonds between chlorine atoms and hydrogen atoms.
19. The thermochemical equation shows the precipitation of lead(II) sulphate.
Which of the following equation will produce the same value for ∆H?
A Pb(NO3)2(aq) + 2KI(aq) à PbI2(s) + 2KNO3(aq)
B Pb(NO3)2(aq) + 2KCl(aq) à PbCl2(s) + 2KNO3(aq)
C Pb(NO3)2(aq) + K2SO4(aq) à PbSO4(s) + 2KNO3(aq)
D Ba(NO3)2(aq) + Na2SO4(aq) à BaSO4(s) + 2NaNO3(aq)
20. The figure shows the energy level diagram for the precipitation of barium sulphate.
Which of the following statement is true?
A Heat energy is absorbed in the reaction.
B The temperature of the mixture increases.
C The products contain more energy than the reactants.
D The energy absorbed for bond breaking is more than the energy released from the bond formation.
21. The thermochemical equation between hydrochloric acid and potassium hydroxide is shown.
HCl(aq) + KOH(aq) à KCl(aq) + H2O(l) ∆H = - 57 kJ mol-1
Which of the following reactions have the same heat of neutralization?
I HNO3(aq) + KOH(aq) à KNO3(aq) + H2O(l)
II HCl(aq) + NH3(aq) + H2O(l) à NH4Cl(aq) + H2O(l)
III ½ H2SO4(aq) + NaOH(aq) à ½ Na2SO4(aq) + H2O(l)
IV CH3COOH(aq) + NaOH(aq) à CH3COONa(aq) + H2O(l)
A I and II only
B I and III only
C II and IV only
D III and IV only
22. The table shows the amount of heat produced when 1 g of a fuel is burnt completely in air.
| Fuel | Heat produced when 1 g of fuel is burnt completely in air (kJ g-1 ) |
| Ethanol | 30 |
| Petrol | 34 |
| Natural gas | 50 |
| Hydrogen | 143 |
Which of the following has the highest fuel value?
A Petrol
B Ethanol
C Hydrogen
D Natural gas
23. The thermochemical equation represents the burning of hydrogen in oxygen:
2H2(g) + O2(g) à 2H2O(l) ∆H = -286 kJ mol-1
Which of the following is the energy level diagram for the reaction?
A
B
C
D
24. The thermochemical equation shows the precipitaion of calcium carbonate.
Na2CO3 aq) + Ca(NO3)2 (aq) à CaCO3(s) + 2NaNO3(aq) ∆H = +30 kJ mol-1
Which of the following energy level diagrams represents the reaction?
A
B
C
D
25. The figure shows the energy level diagram of an endothermic reaction.
Given that the initial temperature of the reactant mixture is 28oC.
Which of the following is true?
| | Value of ∆H (kJ mol-1 ) | Highest / lowest temperature of the product mixture(oC) |
| A | + y | 25 |
| B | - y | 30 |
| C | + y | 30 |
| D | - y | 25 |
26. The thermochemical equation shows the combustion of carbon in oxygen.
C(s) + O2(g) à CO2(g) ∆H = - 393 kJ mol-1
How many moles of carbon, C must be burnt to produce 196.5 kJ of heat?
A 0.2 mol
B 0.5 mol
C 0.8 mol
D 1.2 mol
27. The thermochemical equation shows the diplacement of copper by zinc.
Zn(s) + CuSO4(aq) à ZnSO4(ag) + Cu(s) ∆H = - 190 kJ mol-1
What is the quantity of heat energy released if 6.4 g of copper is displaced?
[Relative atomic mass: Cu, 64]
A 1.9 kJ
B 19 kJ
C 190 kJ
D 1900 kJ
28. P and Q react to produce R and S. The thermochemical equation and energy level diagram for the reaction are given below.
P + Q à R + S ∆H = - a kJ mol-1
What is the value of a?
A x kJ
B y kJ
C (x – y) kJ
D (y – x) kJ
29. The figure shows the energy diagram for the decomposition of calcium carbonate.
Which of the following information can be obtained from the figure?
I The reaction is very fast.
II Heat energy is absorbed during the reaction.
III The activation energy of the reaction is 570 kJ.
IV The reactant has less energy than the products.
A I and II only
B I and III only
C II and IV only
D I, II and IV only
30. 50 cm3 of 1.0 moldm-3 hydrochloric acid is poured into 50 cm3 of 1.0 moldm-3 sodium hydroxide solution. The initial and final temperature are immediately recorded as shown below.
| Initial temperature of hydrochloric acid | 29.0oC |
| Initial temperature of sodium hydroxide solution | 29.0oC |
| Highest temperature of the mixture | 35.0oC |
[Specific heat capacity = 4.2 Jg-1oC-1, density of solution = 1.0 gcm-3]
What is the value of heat released in the reaction?
A 126 J
B 126 kJ
C 2520 J
D 2520 kJ
Questions 31 to 34.
Write the answers in the space provided.
31. Based on the information given below, describe endothermic and exothermic reaction.Use all the information given.
Endothermic reaction – chemical reaction – absorbs heat energy – surroundings Exothermic reaction – chemical reaction – releases heat energy – surroundings
……………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………....……………………………………………………………………………………………………
32. Using the information given below, explain how endothermic and exothermic reactions are applied to produce hot packs and cold packs.
……………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………...………………………………………………………………………………………………………………………………………………………………………………………………………….
33. The energy level diagram shows the reaction in Haber process.
Write 3 information based on the diagram above.
Use all these words in your answer.
reactants, products, exothermic reaction, release energy.
……………………………………………………………………………………………………
……………………………………………………………………………………………………
…………………………………………………………………………………………………....
……………………………………………………………………………………………………
34. The table shows information on some alcohols.
| Alcohol | Formula | Heat of combustion (kJ) |
| Methanol | CH3OH | -726 |
| Ethanol | C2H5OH | -1376 |
| Propan-1-ol | C3H7OH | -2026 |
| Butan-1-ol | C4H9OH | -2679 |
| Pentan-1-ol | C5H11OH | -3332 |
Based on the information, what is the relationship between the number of carbon atoms and the heat of combustion.
……………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………....…………………………………………………………………………………………………….
Listen carefully to the text read by the teacher. Answer questions 35 and 36.
35. Which type of chemicals are used in making hot packs?
A Chemicals that are acidic in nature.
B Chemical that are alkaline in nature.
C Chemicals that react to absorb heat.
D Chemicals that react to produce heat.
36. Hot packs are used to
A Cool down a fever.
B Keep the food cold.
C Reduce swelling when an athlete is injured.
D Warm the hands and feet in the cold weather high up the mountain.
Listen carefully to the text read by the teacher. Answer questions 37 and 38.
37. What do you call the amount of energy that can be obtained when 1 g of fuel is burnt completely?
A Fuel value
B Caloric value
C Energy value
D Combustion value
38. What is the unit used for the heat value?
A J g-1
B kJ g-1
C J mol-1
D kJ mol-1
