Thermochemistry

In an exothermic reaction, the enthalpy change is:

• 1 Positive
• 2 Negative
• 3 Zero
• 4 Infinite

Hess's law states that the enthalpy change of a reaction depends on:

• 1 The speed
• 2 The path taken
• 3 Only the initial and final states
• 4 The catalyst

The standard enthalpy of formation of an element in its standard state is:

• 1 0
• 2 -1 kJ/mol
• 3 1 kJ/mol
• 4 100 kJ/mol

Bond breaking is:

• 1 Exothermic
• 2 Endothermic
• 3 Neither
• 4 Always a catalyst process

Heat of combustion is the heat released when one mole of a substance:

• 1 Melts
• 2 Boils
• 3 Dissolves
• 4 Burns completely in oxygen

The enthalpy change for the reaction C + O2 giving CO2 is -394 kJ/mol. This reaction is:

• 1 Not possible
• 2 Exothermic
• 3 Endothermic
• 4 Thermoneutral

The heat needed to raise 1 g of water by 1 degree C is about:

• 1 0.42 J
• 2 420 J
• 3 42 J
• 4 4.2 J

The standard state of a substance refers to its state at:

• 1 Any pressure
• 2 100 degrees C only
• 3 1 atm pressure and 298 K
• 4 0 atm and 0 K