Question

The enthalpy change for the reaction \( \text{C} + \text{O}_2 \rightarrow \text{CO}_2 \) is \( -393.5 \, \text{kJ/mol} \). What is the heat released when 2 moles of carbon react with excess oxygen?

• A. \( -393.5 \, \text{kJ} \)
• B. \( -787 \, \text{kJ} \)
• C. \( -196.75 \, \text{kJ} \)
• D. \( 0 \, \text{kJ} \)

Hint:

Remember: When a reaction involves more than 1 mole of reactant, multiply the enthalpy change by the number of moles to find the total heat released or absorbed.

Answer 1

The Correct Option is B

Step 1: Determine reaction enthalpy The enthalpy change for \( \text{C} + \text{O}_2 \rightarrow \text{CO}_2 \) is \( -393.5 \, \text{kJ/mol} \). This indicates \( 393.5 \, \text{kJ} \) of heat is released per mole of carbon reacted with oxygen. Step 2: Compute heat released for 2 moles of carbon For 2 moles of carbon, the total heat released is calculated as: \[ \text{Heat released} = 2 \times (-393.5 \, \text{kJ/mol}) = -787 \, \text{kJ} \] Answer: The heat released when 2 moles of carbon react with excess oxygen is \( -787 \, \text{kJ} \). This corresponds to option (2).