Calorimetry Flashcards
define: calorimetry
experimental method which measures heat energy released by the combustion of food/fuel/other chemical reaction.
how can heat b lost?
no lid/burned in open space
how can we reduce heat loss
put lid on calorimeter
insulating calorimeter - reducing heat transfer to env
define: calorimeter
device used to measure energy changes in chemical or physical reactions.
describe solution calorimetry
reaction occurs in solution, no combustion so doesn’t measure heat content
what’s heat content
energy released when a substance is burned
what happens if water temp increases?
heat energy released from reaction, absorbed by water
what happens if water temp decreases?
reaction absorbs heat energy from water
key features of solution calorimeter?
o Accurately known sample of water, combined with a substance to form a solution
o Insulation – reduces heat transfer to/from surroundings
o Thermometer
o Stirrer – ensures temperature of water is uniform.
describe bomb calorimeter
reaction occurs in sealed bomb vessel, enables combustion reactions so can measure energy content
describe sealed bomb vessel
Sample in crucible
It is pressurised, and can withstand high pressures
Contains oxygen.
Electric heater to ignite sample
other features of bomb calorimeter?
o Insulated container
o Thermometer
o Stirrer
in a perfectly insulated calorimeter:
no heat is lost - temp is constant after current is turned off.
in a regular calorimeter:
heat could be lost during/after operating.
lost bc transfered heat to external environment
gained bc transfer of heat could be delayed
how do you take into account heat losses
extrapolation
