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Chemistry Unit 4 > Equilibria > Flashcards

Flashcards in Equilibria Deck (10):
1

Define dynamic equilibrium.

The forwards rate of reaction is equal to the reverse rate of reaction, this makes it seem like there is nothing happening.

2

Where can a dynamic equilibrium be achieved?

In a closed system at constant temperature.

3

Give an expression for the equilibrium constant, Kc, for reaction aA + bB --> dD + eE.

Kc = [D]^d[E]^e all over [A]^a[B]^b

4

What do the powers represent in the equation for Kc?

Number of moles.

5

How do we calculate a value for Kc?

By using the equation, and substituting in values for the concentrations. Remember to turn all moles into concentrations using the volumes given.

6

What are the units for Kc?

The units must be worked out after each calculation, using the units of the values used.

7

What is the only condition that can alter Kc?

Temperature.

8

How does Kc change if you increase the temperature of a reaction, and why?

Increasing the temperature will cause the equilibrium to shift in the endothermic direction as to oppose this change. If more product is formed, Kc will rise, if more reactant is formed Kc will decrease.

9

How does Kc change if you decrease the temperature of a reaction, and why?

Decreasing the temperature will cause the equilibrium to shift in the exothermic direction as to oppose this change. If more product is formed, Kc will rise, if more reactant is formed Kc will decrease.

10

How do catalysts effect an equilibrium and it's Kc?

A catalys will decrease the time it takes for a system to reach equilibrium. It will not, however, effect the position of the equilibrium, or the value of Kc.