Energy Changes Jamb Chemistry Past Questions
Question 1
2KClO\(_3\)(s) → 2KCl(s) + 3O\(_2\)(g)
The importance of the catalyst in the reaction above is that
- A. heating may not be required before the reaction takes place
- B. the reaction is controllable even at a high temperature
- C. the reaction produces large quantity of oxygen
- D. the reaction takes place more rapidly at a lower temperature
Question 2
The heat of formation of ethene, C\(_2\)H\(_4\) is 50 kJmol\(^{-1}\), and that of ethane, C\(_2\)H\(_6\) is -82kJmol\(^{-1}\). Calculate the heat evolved in the process:
C\(_2\)H\(_4\) + H\(_2\) \(\to\) C\(_2\)H\(_6\)
- A. -122kJ
- B. -132kJ
- C. -88kJ
- D. -60kJ
Question 3
The part of the total energy of a system that accounts for the useful work done in a system is known as
- A. Enthalpy change
- B. None of the above
- C. Gibb's free energy
- D. Entropy
Question 4
When sodium nitrate dissolves in water, ∆H is positive. This means that?
- A. the reaction is catalysed
- B. the reaction is complete
- C. the reaction is exothermic
- D. the reaction is endthermic
- E. sodium nitrate is highly soluble in water
Question 5
0.16g of methane when burnt raises the temperature of 100g of water by 40°C. What is the of combustion of methane when if the heat capacity of water is 4.2 Jg-1°C-1?
(CH4 = 16)
- A. 1,160 kJ mol-1
- B. 1,180 kJ mol-1
- C. 1,560 kJ mol-1
- D. 1,600kJ mol-1
- E. 1,680 kJ mol-1
