1 The Reaction Program. 2 Add species windows by clicking + Enter a balanced reaction. Leave Phase...

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The Reaction Program

2

Add species windows by clicking +

Enter a balanced reaction. Leave Phase as most stable.

Press Next

Units can be changed from the units header

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Enter a temperature

Hit calculate

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the reaction

changes in thermodynamic properties for the reaction at 700°C

Why is ΔH negative? Why is ΔG negative?

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Enter a single reactant to calculate ABSOLUTE thermodynamic properties

Absolute Properties

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Enter initial, final and incremental values for a series of temperatures

7When does absolute H = 0? When does absolute S = 0?

Absolute thermodynamic properties for Na. Note phase changes from solid to liquid to gas.

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Plotting results in a figure

Click Figure, then Axes You must have more than one point to plot a figure

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Click Y-variable

Select thermodynamic function and scale Repeat for X-variable

Adjust the range and increment

Press OK

10Note phase transitions at the inflection points of the Gibbs energy function

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How to calculate the effect of temperature or pressure changes

Initial temperature

Final temperature

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Delta properties

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How to calculate properties of a physical change – melting, evaporation

change of phase, constant T

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When does ΔG = 0?

at 900°C, ΔG becomes negative

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At 898.65°C, liquid Na is in equilibrium with 1 atm of Na vapor

Leave T blank and enter zero for ΔG

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What temperature is achieved if the reaction is adiabatic?

We assume it’s hot enough to vaporize NaCl

reactant and product temperatures are different

17Note that all phases must be specified in order to enter values for ΔG, ΔH, etc.

Hotter than normal boiling point of Na

enter 0 for adiabatic reaction

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Non-standard States

Check the non standard states box to enter values for pressure and activity. To make them variables, enter P for pressure or x for activity.

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for equilibrium, set ΔG = 0

1. To determine the partial pressure of chlorine, enter T and x below2. To determine the activity of sodium, enter T and P below3. To determine the equilibrium temperature, enter P and x below

1.2.3.

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Liquid

Gas

Bi + Cd

Bi - Cd1 atm

mole fraction Cd

T(C

)

0 0.2 0.4 0.6 0.8 10

200

400

600

800

1000

1200

1400

1600

The Bi-Cd phase diagram consists of a vapor phase, a liquid solution and pure solid metals. What can we change to lower the boiling point of Cd? Second, what can we change to lower the melting point of Cd?

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We can lower the boiling point by decreasing the pressure

vapor-liquid equilibrium

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vary the pressure in steps of -0.2 atm and set ΔG=0

as pressure decreases, the boiling temperature drops

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P-T relation for equilibrium between phases

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Pressure has very little effect on melting point. However, lowering the activity of Cd by putting it in a liquid will decrease the melting point, but only up to the eutectic.

solid-liquid equilibrium variable activity

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as activity decreases, the melting temperature goes down