Question

In a combustion reaction, heat change during the formation of 40 g of carbon dioxide from carbon and dioxygen gas is (Enthalpy of combustion of carbon = -396 kJ mol\(^1\))

• A. 320 kJ
• B. -320 kJ
• C. -360 kJ
• D. 360 kJ
• E. 240 kJ

Hint:

To calculate heat change, use the enthalpy of combustion and multiply it by the number of moles involved in the reaction.

Answer 1

The Correct Option is C

Step 1: The moles of CO\(_2\) are calculated using its molar mass (44 g/mol), yielding 40/44 = 0.909 moles of CO\(_2\).
Step 2: The heat change is then calculated using the enthalpy of combustion for carbon: \[ {Heat change} = 0.909 \times (-396) = -360 \, {kJ}. \]