Question

What will be the final temperature of 650 g of water initially at 5.5°C if it is heated by burning 7.5 g of carbon to carbon dioxide. The molar heat of reaction is -393.5 kJ/mol.

I do not understand how to do this question

Answer 1

heat to water = q = mass H2O x specific heat H2O x (Tfinal-Tinitial). You don't know q or Tfinal. But you can calculate q this way, then solve for Tfinal.

The problem tells you that burning 1 mol carbon to produce CO2 gas gives 393.5 kJ of heat. How many mols do you have? That's 7.5g/12 = ? mols carbon so you should produce for q 393.5 kJ/mol x (?mol) = ? kJ. Change that to J and substitute into the equation above and solve for Tfinal.