Investigation of Action of Saliva and 3 M Hydrochloric Acid in Two Carbohydrate Solutions
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Chapter Scopes
• Endothermic & Exothermic reactions
• Enthalpy changes: ∆H of formation, combustion, hydration, neutralization, atomization. CHAPTER 5
Chemical Energetic /
Thermochemistry
• Lattice energy, electron affinity
• Heat of fusion and vaporization
• Hess’ Law
• BornHaber cycles
• Calorimetry
© 2006 Brooks/Cole  Thomson
© 2006 Brooks/Cole  Thomson
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Energy & Chemistry
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Thermochemistry
• Thermochemistry is the study of heat (energy) change/transfer in a chemical reaction.
• ENERGY is the capacity to do work or transfer heat. • HEAT is the transfer of thermal energy between two objects because of their difference in temperature.
Heat …show more content…
Specific Heat Capacity, Cs
But we use the unit called the
JOULE
1 cal = 4.184 joules
The amount of heat (q) required to raise the T of
1 gram of the substance by 1 C or 1 K
James Joule
18181889
© 2006 Brooks/Cole  Thomson
Specific Heat Capacity, Cs
• How much energy is transferred due to T difference?
• The heat (q) ―lost‖ or ―gained‖ is related to
© 2006 Brooks/Cole  Thomson
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Change in Temperature (T)
T of
System
Sign of
Tsystem
Sign of q
Direction of Heat
Transfer
Increase
+
Tfinal >Tinitial
+
Decrease


Heat transferred from surroundings to system
(_____thermic)
Heat transferred from system to surroundings (_____thermic)
a) sample mass
b) change in T and
c) specific heat capacity
Tfinal Tinitial
Specific heat capacity = heat lost or gained by substance (J)
(mass, g)(T change, K)
© 2006 Brooks/Cole  Thomson
FHSC1114 Physical Chemistry
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© 2006 Brooks/Cole  Thomson
2
Centre for Foundation Studies, UTAR
Heat Transfer
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q = m x Cs x T q = C x T
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Example 1: If 25.0 g of Al cool from 310oC to 37oC, how many joules of heat energy are lost by the Al?
(specific heat capacity of Al = 0.897 J g1 K1)
Solution:
q = heat absorbed or released (J)
Cs = specific heat (J g1 K1)
C = heat capacity (J