# Packet by nuhman10

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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.
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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

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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 =

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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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