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 What is the formula for Gibbs Free energy?  What does each variable represent?  How can you tell if a reaction will be spontaneous?  How can you tell.

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Presentation on theme: " What is the formula for Gibbs Free energy?  What does each variable represent?  How can you tell if a reaction will be spontaneous?  How can you tell."— Presentation transcript:

1  What is the formula for Gibbs Free energy?  What does each variable represent?  How can you tell if a reaction will be spontaneous?  How can you tell if a reaction is exothermic or endothermic?  What is entropy?  Determine if the following reaction will be spontaneous/nonspontaneous, exo/endo, increase/decrease is entropy  ΔH= -26700 J, T= 387, ΔS= -234

2 1. Name one property of a solid, liquid, and gas. 2. Separate the phase changes into endothermic and exothermic processes. 3. How do you find the boiling point of a substance on a phase change diagram? 4. Draw a sketch of a phase change diagram and label the solid, liquid, and gas phases. 5. How do you know a state change is taking place on a freezing and boiling point graph? 6. How many moles of a gas are present at a pressure of 798 torr, a volume of 278 mL, and a temperature of 45 o C? 7. How many liters of NH 3 can be made from 5.6 g of H 2 ? 1. N 2 + 3H 2  2NH 3 8. What is the specific heat of a 4.3 g piece of metal that absorbs 1987 J of heat energy and the temperature changed from 16 o C to 54 o C 9. Using the Gibbs free energy equation, describe the following process: 1. ΔH= -25 KJ, T= 124 K, and ΔS= 5.o KJ/K

3 Pg. 107

4  Nature of reactants (how reactive they ARE)  Concentration:  Reaction speed increases when concentration of reactants increases  Surface area:  Increased surface area leads to increased reaction rate  Temperature:  Increased temperature allows for a greater chance of collision  Catalysts:  Causes a lower activation energy

5  Most reactions do not go to completion. They are reversible  Use a double arrow to show that an equation can be reversed  Chemical equilibrium happens when the forward and backward reactions balance each other because they take place at equal rates  As the concentration of reactants decrease, concentration of products increase

6  The formation of NH 3. Used in fertilizers  N 2 + 3H 2 2NH 3

7  Can determine equilibrium constant- K eq  Concentrations of the products raised to the power of their coefficients/ concentrations of the reactants raised to the power of their coefficients  aA + bB cC + dD K eq = ([C] c [D] d )/ ([A] a [B] b )  K > 1: more products than reactants @ equil  K < 1: more reactants than products @equil

8  Write the expression for finding the equilibrium constant for the following reaction:  N 2 + 3H 2 2NH 3  Find the equilibrium constant if the concentration of N 2 is 0.533 mol/L, H 2 is 1.600 mol/L, and NH 3 is 0.933 mol/L

9  Says if a stress is applied to a system at equilibrium, the system shifts in the direction that relieves the stress  Can predict how changes in temp, concentration, and volume (pressure) will effect equilibrium  V and P related- if you increase the volume, you decrease the pressure  Longer arrow shows which way equilibrium will shift ( or )

10  An increase in the concentration of a reactant shifts the reaction toward the product  Ex. CO +3H 2 CH 4 + H 2 O  If products are removed, it will shift toward the products

11  If you decrease the volume (increase pressure) reaction will shift to the side with the smaller amount of moles.  Ex. CO +3H 2 CH 4 + H 2 O

12  The reaction will shift in the opposite direction when the temperature is added  Exothermic  shift to left  Endothermic  shift to right


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