Which will require more heat, increasing the temperature of 1 mol of C8H18(l) by a certain amount or increasing the temperature of 1 mol of H2O(l) by the same amount?

Increasing the temperature of 1 mol of C8H18(l) requires more energy

Explanation:

To answer this question, we need to define molar heat capacity that is the amount of heat required to increase in 1K the temperature of 1 mole of substance.

That means the substance with higher molar heat requires more energy to increase its temperature

Molar heat of octane, C8H18 is 255.68J/Kmol

Molar heat of water is 75.38J/Kmol

That means increasing the temperature of 1 mol of C8H18(l) requires more energy