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Solution Equilibrium
Equilibrium Constant
Le Chatelier's Principle
Topic 8
100
Is solution equilibrium a physical or chemical equilibrium? Why?
Physical, solutions are a physical change. It doesn't obey the rules of chemical equilibrium.
100

How does one calculate the equilibrium constant?

[product]coefficientx[product]coefficient/over

[reactant]coefficient x[reactant]coefficient

100

What does Le Chatelier's principle state?

That a system at equilibrium will resist any stress put upon it.

100

Why does the rate of reaction change with an increase in temperature.

Equilibrium constant is temperature dependent, and the reactants will have a greater nubmer of effective collitions and the higher average kinetic energy.

200
What is equal in solution equilibrium?
The rate of dissolving and the rate of crystalization.
200

Write the equilibrium constant expression for electrolysis of liquid water into H2 and O2.

2H2O(l) ---> 2H2(g) + O2(g)

Keq = [H2]2(eq)x[O2](eq)

200

If you wanted to change the K value of a system at equilibrium what must you change?

What is Temperature?

200

A solution that has dissolved as much solute as it can and then has had the temperature reduced is called what?

Supersaturated.

300
Which of the three states of concentration of a solution (unsaturated, saturated and supersaturated) can equilibrium occur in?
Saturated.
300

What is the equation for K for displacement reaction Zn(s) + 2AgCl(aq) = 2Ag(s) + ZnCl2(aq)

[ZnCl2](aq)/[AgCl]2(aq)

300

Describe what happens to the chemical system 

A + B = C + D + 57kJ,  when the temperature is increased.

The forward rxn is exothermic in which heat is the product. Adding more product will shift the equil-m to the left to produce more reactants. 
300

Why doesn't a catalyst effect the K value?

A catalyst lowers the rates of both forward and reverse rxns, allowing the eq-m to be achieved faster but does not change the position of the equilibrium or the Keq value.

400

Will the additional of 5 g of solid placed into a beaker with saturated solution dissolve if the conditions remain the same?

Yes, however new solute will also form at the same rate as the rate of dissolution.

400

Ca3(PO4)2(s) = 3Ca2+(aq) + 2PO43-(aq)

[Ca2+]3x[PO43-]2 

400

For the reaction X2(g) + 3Y2(g) = 2XY3(g) at equilibrium; what would be the result of decreasing the amount of X2?

The equilibrium would shift to the left to compensate for the loss of the reactant. 

400

If two reactant particle impact each other and do not form the activated complex, give two reasons why they may have a successful impact in the future.

They may hit each other with a more proper orientation and a higher energy.

500

If a solution is saturated with excess solute and the temperature is increased, describe what will happen to the solute immediately and after the temperature returns back to the original value? 

What will happen to the equilibrium?

Solute dissolves and remains dissolved. Equilibrium will be met and then lost if solution will be supersaturated.

500

HCN(aq) = H+(aq) + CN-(aq)                                                                                         [HCN]eq= 0.25M    [H+]eq=1.5x10-4M      [CN-]eq=2.3x10-3M

What is the Keq value? 

Keq = ([H+]x[CN-])/[HCN] = 1.4 x 10-6

500

For the reaction X2(g) + 3Y2(g) = 2XY3(g) at equilibrium; what would be the result of decreasing the pressure?

There 4 moles of gas on the reactant side and only 2 mols of gas on the product size. If the pressure is decreases the concentrations of reactant would be lower, the equilibrium would shift to the left. 

500

What is the difference between a catalyst and a reaction intermediate?

Catalysts exist at the begining and end of a reaction but, whereas intermediates disappear at the end of the reaction.