THERMODYNAMIC

What are thermodynamics?

The study of energy changes during chemical and physical changes

What is two factors favor spontaneous reactions?

* Decrease in energy of system: Enthalpy.
* Increases in randomness of system: Entropy.

When a bond is formed __________

E released

When a bond is broken **____________**

E required

What is potential energy?

ability of a substance to react.

In what forms is energy released?

Released as **heat or light** during reaction as more stable products formed

**strong bonds =**

**Lower PE state, more stable**

weak bonds =

higher PE state, less stable

__**Formation of nitrogen triiodide**__

2NI3 → 2N2 + 3I2 + E

Given that this reaction is____, compare the bond energies of the products and reactants.

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exothermic

More E released on __**____**__ than is required to __**___**__

Forming product bonds, break reactant bonds

**Bond E of P __bond E of R**

**Bond E of P > bond E of R**

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**Which has weaker bonds, reactants or products?**

R

**Which has higher PE value, reactants or products?**

R

**Which are more stable, reactants or products?**

P

**PE of system increase or decrease?**

Decrease. PE converted to KE.

What are properties of state functions?

__**State Functions (Properties)**__

* Properties of a system that depend only on __**system’s current state, not past**__ 

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* independent of __**pathway**__

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* Amount of E is a state function; T, V and P also

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Properties of a system that depend only on____**, not ___**__

Properties of a system that depend only on __**system’s current state, not past**__ 

independent of __**___**__

independent of __**pathway**__

__**Heat and work**__ **transferred to/from system are not state functions, but ___**

__**Heat and work**__ **transferred to/from system are not state functions, but** __**path functions**__

What is **enthalpy or heat of reaction?**

E flow for a reaction at constant P.

An extensive property: ____

depends on amount present.

Never know exact enthalpy values only **ΔH:**

= **Hprod. - Hreact.**

For a given material or substance, the standard state is the ____for the material's thermodynamic state properties such as enthalpy, entropy, Gibbs free energy, and for many other material standards..

reference state (trạng thái tham chiếu)

The standard enthalpy change of formation for an element in its standard state is zero,

and this convention allows a wide range of other thermodynamic quantities to be calculated and tabulated. 

__Thermodynamic Standard State__

* Most stable form of a substance at __**1 atm**__ and __**25°C**__
* __**1 M concentration**__ **for all substances in solution**

**ΔH° =** __**Standard**__ **enthalpy of rxn** 

**What would happen to the T of the water?**

It would ↑ (water = surroundings) 

H released by system, absorbed by water

* It would ↑ (water = surroundings)
* H released by system, absorbed by water.

__Specific Heat Capacity (c)__

* Heat required to raise __**1.0**__ __**g of a substance 1°C**__


* Used for __**reaction within calorimeter.**__
* J/ g•oC   
* For water = 4.184 J/ g•oC

__Molar Heat Capacity__

* Heat required to raise 1.0 mol of a substance 1°C
* J/mol•oC

__**Converting from specific heat to molar heat capacity**__