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									                                      Thermodynamics
                                                                  Name: ____________________

                                                                          Period: _____________


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Thermodyna mics
Uni t Begins




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Review              Thermodynamics
Lab Due             Unit Ends
Homework Due
                    Packet Due



                                     California Standard


 Chemical Thermodynamics

 7. Energy is exchanged or transformed in all chemical reactions and physical changes of
 matter. As a basis for understanding this concept:
     a. Students know how to describe temperature and heat flow in terms of the
        motion of molecules (or atoms).
     b. Students know chemical processes can either release (exothermic) or absorb
        (endothermic) thermal energy.
     c. Students know energy is released when a material condenses or freezes and is
        absorbed when a material evaporates or melts.
     d. Students know how to solve problems involving heat flow and temperature
        changes, using known values of specific heat and latent heat of phase change.

 Thermoche mistry: the study of energy changes that occur during chemical reactions and
 changes in state.

 Che mical potential ene rgy: The energy stored in the chemical bonds of a substance. (the kinds
 of atoms and their arrangement)

 Heat: q, energy that transfers from one object to another because of the temperature difference.
                                                 1
                  Endothermic                                           Exothermic




N 2 (g) + O 2 (g) + 43 kcal → 2 NO(g)                 CaO(s) + H2 O(l) → Ca(OH)2 (s) + 65.2 kJ
                                        ∆H = +43 kcal                                     ∆H = -65.2 kJ

2NaHCO 3 (s) + 129 kJ → Na2 CO3 (s) + H2 O(g) +  Fe2 CO3 (s) + 3CO(g) → 2Fe(s) + 3CO 2 (g) + 26.3 kJ
CO 2 (g)                                                                            ∆H = -26.3 kJ
                                    ∆H = +129 kJ


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Unit of measuring heat flow

Specific Heat




Heat Capacity




Calculate the following. Show all work
Specific heat of water                        4.184 J/g°C or 1.00 cal/ g°C
Specific heat of ethanol                      2.452 J/g°C

1. How much heat is required to raise the temp of 100 g of water from 0°C to 50°C?




2. If 7356 J were added to 200 g of ethanol, its temp would go up by how much?




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Heat changes in state

Heat of fusion ∆Hf = -∆Hsolid                       Unit: kJ/mol, J/g, cal/g
Heat of solidification
Heat of vaporization ∆Hv = -∆Hcond                  Unit: kJ/mol, J/g, cal/g
Heat of condensation
Heat of Solution                                    Unit: kJ/mol, J/g, cal/g




                                     Heat of Physical Change

           Subtance                         ∆Hf (J/g)                          ∆Hv (J/g)
 Ethanol (C2 H5 OH)
 Water (H2 O)                                 334                                2260




                                                4
Show All Work:
3. How much heat (in kJ) is absorbed when 2.0 mole H2 O (l) at 100ºC and 101.3 kPa is
   converted to steam at 100ºC?

   liquid→gas:




4. How many kilo joules of heat are released when 25 g of ethanol, C2 H5 OH(g) condenses at its
   normal boiling point?



   gas→liquid:



5. How much heat is required to change 15.0 g of ice at 0.0°C into water and then raise the
   water temp to 20.0°C?



   solid→liquid: q1 = gram x ∆Hf =                     x                  =

   liquid 0ºC→20ºC: q2 = m x C x ∆T =                  x           x(         -       )=

   Q = q1 + q2 =




6. When 20.0 g of steam at 100ºC and 101.3 kPa condenses to water and then cool off to
   80.0°C, how much heat was released?


   gas→liquid: q1 = gram x ∆Hv =                   x                    =

   liquid 100ºC→80ºC: q2 = m x C x ∆T =                    x         x(           -    )=

   Q = q1 + q2 =




                                               5
                                               Name: ___________________ Period: ________
                            Thermochemistry Worksheet
Show all work:
1. Calculate the heat lost when 50 gram of water freezes at 0ºC




2. Calculate the heat released when 30 gram of water vaporizes at 100ºC




3. Calculate the heat released when 10 grams of steam at 100ºC and 101.3 kPa condenses to
   water and the water continues to cool to 50ºC.




4. Calculate the heat absorbed when 40 grams of water at 80ºC and 101.3 kPa is heated and
   convert to steam.




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