(ppt) Chapter 7.3 Calorimetry
Three implications of water having a high specific heat
- Can absorb a lot of heat without a large temperature increase - Keeps temperatures stable on Earth - Effective coolant as a fluid
What two types of calorimeters are there?
- Coffee cup calorimeter - Bomb calorimeter
What four reactions can coffee cup calorimeters measure?
- heat of neutralization - heat of ionization - heat of fusion - heat of vaporization
what two things are bomb calorimeters used to determine?
- heats of combustion - number food calories we consume
What components make up a coffee cup calorimeter?
- two nested styrofoam cups - cover - stirrer - thermometer
formula to find qreaction
-(qsolution/water + qcalorimeter)
Specific heat definition
Amount of heat required to raise the temperature of 1 gram of the substance by 1 degree Celcius
Instrument to use for calorimetry
Calorimeter
Symbol for calorimeter constant
Ccal
Unit for temperature in formula to find heat associated with temperature change
Celsius, not kelvin
Symbol for specific heat
Csp
What does a calorimeter measure?
Heat associated with chemical reactions
Calorimeter constant definition
Heat capacity of the calorimeter // amount of heat absorbed by the calorimeter for each degree rise in temperature
qreaction (qrxn)
Heat of reaction/change in enthalpy (deltaH)
Does water have a low or high specific heat?
High
What variable is constant for coffee cup calorimeters?
Pressure
Calorimetry
Science of measuring heat
Fundamental equation of calorimetry
The heat lost by a reaction is gained by the surrounding water and calorimeter
Two different metals with same mass subjected to the same amount of heat: which one has the smallest change in temperature?
The metal with the higher heat capacity
What variable is kept constant in a bomb calorimeter?
Volume
formula for bomb calorimeter
deltaE
Formula for bomb calorimetry
deltaE = qrxn = -Ccal x deltaT
Formula for coffee cup calorimeter
deltaH
what does Ccal mean?
heat capacity of the calorimeter and its contents
purpose of inner cup in coffee cup calorimeter
holds solution where reaction occurs
what type of system is a coffee cup calorimeter?
isolated
Unit for calorimeter constant
kJ/C degrees
unit for Ccal
kJ/Celcius
for constant-volume calorimetry, is work done?
no, because volume is constant
Is energy content a negative or positive quantity?
positive
purpose of outer cup in coffee cup calorimeter
provides extra insulation
Formula to find heat associated with temperature change
q = mCsp(deltaT)
what does qrxn mean?
quantity of heat from the reaction mixture
System in coffee cup calorimetry
reactants and products (the reaction)
What is constant-volume calorimetry used to study?
the energy changes in reactions under a constant volume
Bomb calorimetry: what is the energy released from the reaction equal to?
the heat capacity of the calorimeter
surroundings in coffee cup calorimetry
water (solution) and the calorimeter
