calorimetry

Calorimetry

• Quantitatively measures energy changes

• isolated system has no transfer of energy/matter

• calorimeter - isolated system measuring heat released/absorbed by physical/chemical process within

burning a sample

• dry biomass in a calorimeter

• heats a known volume of water

• change in temperature of water provides estimate of chemical energy sample contains

• Heat Lost = - heat gained

Calorimeter

isolated system that measures heat lost or gained

Assumptions of calorimeter

• system is isolated

• thermal energy transfered to calorimeter is negligible

• substances react/dissolve in water in calorimeter, solution has properties of water

• constant pressure

Principles of Calorimetry

• heat from a higher temperature transfers to lower temperature

• higher temperature releases heat, lower temperature absorbs heat

• law of consrvation of energy

Law of Conservation of Energy

total heat lost equal to the total heat gain

the system

• Q = nΔ_rH_m

• chemical burned in calorimeter

• mols

the surroundings

• Q = mcΔT

• water and calorimeter

• grams

molar enthalpy calculation from calorimeter

• nΔ_rH_m = - mcΔT

• nΔ_rH_m - chemical side

• - mcΔT - water/surrounding side

neutralization

• water is the surroundings

• add the masses together