Calorimetric Equations
Putting it Together
Calorimetry
What is Calorimetry?
What is a Calorimeter?
Three Assumptions of Simple
Calorimeters:
1. No heat is transferred between the
calorimeter and the outside environment
2. Any heat absorbed or released by the
calorimeter materials, such as the container,
is negligible
3. A dilute aqueous solution is assumed to
have a density and specific heat capacity
equal to that of pure water (1.00g/ml and
4.184 J/g°C)
 Solution
 Combustion
 Neutralization
Remember what we’ve seen
 ΔH = nΔHx
 ΔHsystem = ±|qsurroundings|
 q = mcΔT
 n = m/MM
n=CxV
Doing Calorimetric problems
is about using these
equations
ΔH = nΔHx
ΔHsystem = ±|qsurroundings|
nΔHx = qsurroundings
nΔHx = mcΔT
n = mcΔT / ΔHx
m/MM = mcΔT / ΔHx
Calorimetry of Solution
 One substance dissolves in another
NaBr(s)  Na+(aq) + Br-(aq)
Heat of Solution Demo
 http://www.teachersdomain.org/resource/lsps07.sci.phy
s.matter.dissolvesalt/
Question 1
 In a calorimetry experiment, 7.46 g of
potassium chloride is dissolved in 100.0
mL (100.0 g) of water at an initial
temperature of 24.1°C. The final
temperature of the solution is 20.0°C.
What is the molar enthalpy of solution of
potassium chloride?
Question 2: On your own
 What mass of lithium chloride
must have dissolved if the
temperature of 200.0 g of water
increased by 6.0°C? The molar
enthalpy of solution of lithium
chloride is –37 kJ/mol.
Calorimetry of Combustion
 Burn a substance in oxygen to yield
CO2 and H2O
C3H8(l) + 5O2(g)  3CO2(g) + 4H2O(l)
Question 3
 If the molar enthalpy of combustion
of propane is -2220KJ/mol, what
mass of propane will have to be
burned in order to raise the
temperature of 1.00L of water from
50.0 to 85°C.
Question 4
 A calorimeter (C=0.850J/˚C)
containing 5.00 x 102 ml of water at
22 oC is warmed to 100oC when
9.00 g of cheddar cheese is burned.
Calculate the heat absorbed by the
water and the heat of combustion,
per gram, of cheese.
Calorimetry of Neutralization
 Acid + Base  Salt + Water
 HCl(aq) + NaOH(aq)  NaCl(aq) + H2O(l)
 Use the same strategy for other reactions
 CuSO4(aq) + 2NaOH(aq) → Cu(OH)2(s) + Na2SO4(aq)
Question 5
 A chemist wanted to find the heat of neutralization of
HCl with NaOH. She added 61.1ml of 0.543M HCl to
42.6ml of 0.779M NaOH. The initial temperature of both
solutions was 17.8oC and the highest recorded
temperature of the solution after neutralization was
21.6˚C. What is the enthalpy of neutralization of HCl?
 ASSUME: The density and heat capacity of the
solutions is the same as that for pure water
Question 6
 50.0 mL of 0.300 mol/L CuSO4 solution is mixed with
an equal volume of 0.600 mol/L NaOH. The initial
temperature of both solutions is 21.4oC. After mixing
the solutions in the coffee-cup calorimeter, the highest
temperature that is reached is 24.6oC. Determine the
enthalpy change of the reaction.
 CuSO4(aq) + 2NaOH(aq) → Cu(OH)2(s) +
Na2SO4(aq)