The following diagrams represent the equilibrium state at 3 different temperatures for a reaction involving substance A and A_2. Let each box represent 1 L and each particle 1 mole. Write a balanced equation for the reaction. Determine the equilibrium constant at each temperature. Does the equilibrium constant increase or decrease with temperature? Explain your answer. Does the reaction proceed forward or in reverse as temperature increases? Is this reaction exothermic or endothermic? Explain your answer. Predict how the number of A and how the number of A_2 molecules would change if the volume were decreased at constant temperature.
2) Which of the following is true regarding the effect of acatalyst on chemical equilibrium?
a.
Only the forward rate increases so the quantity of productsincreases.
b.
Only the forward rate increases but the quantity of productsremains the same.
c.
Both the forward and reverse rates increase and the quantity ofproducts increases.
d.
Both the forward and reverse rates increase but the quantity ofproducts is unchanged.
e.
The effect varies depending on whether the reaction isendothermic or exothermic.
3) The equilibrium constant for a given reaction __________
a.
does not change with temperature.
b.
always increases with temperature.
c.
always decreases with temperature.
d.
increases with temperature for exothermic reactions only.
e.
increases with temperature for endothermic reactions only,
Fill in the blanks
1) Chemical equilibrium arises from the __________ of chemicalreactions and is defined when the __________ of the forwardreaction is equal to the __________ of the reverse reaction.
2) Students often write expressions for the equilibrium constantKc and reaction quotient Qcin exactly the same way. To avoid confusion, you must rememberthatKc uses concentrations under __________conditions while Qc uses concentrations under__________ conditions.
3) If Q for a reaction is greater than K, thereaction will be __________. If Q for a reaction is lessthan K, the reaction will be __________. If Q fora reaction is equal to K, the reaction will be__________.
4) How and why are the expressions for homogeneous equilibriumconstants different from the expressions for heterogeneousequilibrium constants?