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Two types of calorimeters: (1) Bomb calorimeter: rigid steel vessel, constant volume. Measures delta_U (= qv). q = C_calorimeter x delta_T. To find delta_H: delta_H = delta_U + delta_ngas*RT. Used for combustion reactions. (2) Coffee-cup calorimeter: open container, constant pressure. Measures delta_H (= qp) directly. q = m x c x delta_T, where c = 4.184 J/(g.K) for water. Common in acid-base neutralisation experiments. For neutralisation: delta_H = -q/moles of limiting reagent (negative sign if temperature rises, indicating exothermic). Assumptions: no heat loss to surroundings, specific heat of solution equals that of water, density of dilute solution equals 1 g/mL. Calibration of bomb calorimeter uses benzoic acid (known delta_Hc). Key conversion: 1 cal = 4.184 J. When water is a product: check whether it forms as liquid (standard state) or gas — this affects delta_H by 44 kJ/mol per mole of water.