How we can measure enthalpy changes? How to get ΔH for a reaction?
Constant Pressure Calorimeter (neutralization or dissolution):
Polystyrene drinking cup and a vacuum flask or metal can
Known amount of reactants and volumes of liquids is known
Temperature change is recorded
Energy transferred as heat and enthalpy change: ΔH= -mcΔT
ΔH is enthalpy change in J
m is mass of liquids in grams usually water (1cm3 =1g)
C is specific heat capacity in J g-1 oC-1 (for water is 4.18 J g-1 oC-1 )
ΔT is temperature in oC
Constant volume calorimeter:
Bomb calorimeter for measuring combustion reaction:
Energy transferred as heat and enthalpy change: ΔH= -mcΔT
ΔH is enthalpy change in J
m is mass of liquids in grams usually water (1cm3 =1g)
C is specific heat capacity in J g-1 oC-1 (for water is 4.18 J g-1 oC-1 )
ΔT is temperature in oC
Examples are included in the video
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