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A. An exothermic reaction will create _______
B. Is an exothermic reaction is a product or reactant? |
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Definition
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A. An endothermic reaction will produce ________
B. Is an endothermic reaction a product or reactant? |
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Definition
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| Define "Change in Enthalpy" "ΔH" |
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Definition
| The energy that accompanies a chemical reaction |
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A. ΔH is positive for _________ reactions.
B. ΔH is negative for _________ reactions. |
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Definition
A. Endothermic
B. Exothermic |
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An example of enthalpy:
When CH4 undergoes complete combustion, the change in enthalpy of the reaction is -803.1kJ. Where would -803,1kJ go in the chemical reaction?
CH4 + 2O2 ---> CO2 + 2H2O |
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Definition
You would include it in your reactancts since it is exothermic.
CH4 + 2O2 ---> CO2 + 2H2O + - 803.1kJ |
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Use bond energies to answer this question:
How much energy is absorbed or released (identify which) when the following reactions takes place?
CH4 (g) + 2 O2 (g) -->CO2 (g) + 2 H2O (g)
The relevant bond energies are:
C—H 414 kJ/mol
O=O 502 kJ/mol
C=O 730 kJ/mol
O—H 464 kJ/mol
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Know this formula:
ΔH = Energy required to break bonds
- Energy released when bonds form |
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Definition
| Study Example 13.2 on page 425, 426, 427 |
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Definition
| Enthalpy is a state function and is therefore independent of path. |
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| What are standard conditions? |
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Definition
| Most chemistry is done at room temperature of 25º Celcius and 1.00 atm |
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Know 13.9 formula:
ΔHº = Σ ΔHfº(products) - Σ ΔHfº (reactants) |
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Definition
| Study example 13.3 on pages 432-433 |
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| Study example 13.4 on page 434-435 |
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Definition
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Study energy diagrams
Know how to interpret if it is an exothermic or endothermic reaction
Know how to figure ΔH ina diagram |
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Definition
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| Define "The Second Law of Thermodynamics" |
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Definition
| The entropy of the universe must always either increase or remain the same. It can never decrease. |
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| Which state of matter has the highes amount of entropy? |
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Definition
| Gas is the highest, then liquid is second and solids are last. |
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A. Entropy of a system _________ with increasing temperature.
B. Entropy of a system _______ as the matter increases |
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Definition
A. Increases
B. Increases |
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Know formual 13.11
ΔSuniverse ≥ 0 |
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Definition
| Study example 13.6 on pages 442-443 |
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Know 13.12 formula:
ΔS° = Σ S° (products) - Σ S° (reactants) |
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Definition
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Know the "Gibbs Free Energy" formula (13.13)
ΔG = ΔH - T*ΔS
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Definition
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Know:
When ΔG < 0, then the reaction is consisitent with the Second Law and is thus spontaneous.
When ΔG > 0, then the reaction cannot proceed, because it violates the second law |
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Definition
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Know this formula (13.14)
ΔGº = Σ ΔGfº (products) - Σ ΔGfº (reactants) |
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Definition
| Study example 13.7 on pages 448-449 |
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