SK025 CHAPTER 2 THERMOCHEMISTRY

1. The change in enthalpy of solution for an ionic solid __________________.

• is always positive
• is always negative
• can be positive or negative
• is always zero

2. Which of the following substances has value of enthalpy formation is zero (0)?

• Chlorine gas
• Pure water
• Liquid ammonia
• Solid carbon dioxide

4. The quantity of heat needed to raise the temperature of a sample of a substance by one degree Celsius is the definition of

• Specific heat capacity
• Heat capacity
• Calorimeter
• Enthalpy

5. Why is the lattice energy of Na₂O is higher than that of K₂O?

• Sodium has a higher charge density
• Potassium has more electrons than calcium
• The ionic radius of sodium is smaller
• The melting point of sodium oxide is higher

6. The diagram shows the energy profile diagram for the formation of ethene . Based on the information given, choose the correct statement.

• I only
• I and II
• II and III
• I, II and III

7. The enthalpy of combustion for hydrogen gas is -286 kJ/mol. Which of the following statements is NOT TRUE?

• The reaction is exothermic.
• Hydrogen gas was combusted in an excess oxygen gas to produce water.
• The enthalpy of formation of water is +286 kJ/mol.
• If 0.5 mole of hydrogen gas is combusted, the amount of heat released is lower than -286 kJ/mol.

8. Which of the following cannot be found in a Born-Haber cycle?

• Electron affinity
• Ionisation energy
• Enthalpy of atomisation
• Enthalpy of combustion

9. Electrovalent compound that has the largest magnitude of lattice energy

• NaF
• RbF
• CsF
• KF

10. Which of the following is true about the Born-Haber cycle?

I. It is closely related to Hess’s Law.

II. It must include the enthalpy of formation of an ionic crystal.

III. It can be used to determine the enthalpy of solution

• I only
• I and II
• II and III
• I, II and III

11. Endothermic reaction is a reaction in which the heat is ___________ from the surroundings.

• released
• absorbed
• changed
• used