15.1.3 Converting Between Kc and Kp Flashcards Preview

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Flashcards in 15.1.3 Converting Between Kc and Kp Deck (12)
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1
Q

Converting Between K c and K p

A
  • The values of K c and K p at a given temperature are often not the same.
  • The value of K p can be converted into the value for K c : K p = K c (RT) Δn .
2
Q

note

A
  • The Haber-Bosch process is an example of a reaction in which the values of K c and K p are not the same. When the reaction to the left was allowed to achieve equilibrium, the partial pressures of the component gases were found to be as shown on the left. The equilibrium expression can be in the form of partial pressures or in the form of concentration. The equilibrium constant found using partial pressures is
    denoted K p .
  • It is possible to convert the value of K p into a value of K c at a given temperature. The ideal gas law can be rearranged to illustrate how pressure and concentration are related to one another.
  • The first step is to rearrange the ideal gas law as shown on the left.
  • Next, substitute the rearranged ideal gas law for each gas into the K c expression, as shown on the left in step two.
  • The third step is to factor out the (RT) Δn term. Finally, rewrite the expression in terms of K p . The final equation shows the relationship between K c and
    K p : K p = K c (RT) Δn
3
Q

True or false?

The term Δn, in the equation relating Kp and Kc, the value for Kp = Kc (RT)Δn, cannot be zero.

A

false

4
Q

Ammonia is synthesized in the following reaction
N2(g) + 3H2(g) -> 2NH3(g)
The Kc and Kp values were 0.105 and 0.000028, respectively. At what temperature did this reaction take place?

A

745 K

5
Q

For the following reaction in which ammonia is synthesized, the equilibrium constant, Kc, is 0.65 at 375 degrees C.
N2(g) + 3H2(g) -> 2NH3(g)
Initial concentrations of H2, N2, and NH3 are 0.76M, 0.60M, and 0.48M, respectively. In which direction will the reaction proceed to reach equilibrium

A

right to left

6
Q

The Haber process involves the synthesis of ammonia from nitrogen and hydrogen
N2(g) + 3H2(g) ->

A

1.3

7
Q

In the ideal gas equation, the volume, V, ____________________

A

varies inversely with pressure.

8
Q

For the following reaction, the equilibrium constant Kp is 0.0005 at 300 degrees C. What is the value of Kc?
2SO3(g) -> 2SO2(g) + O2(g)

A

0.0000106

9
Q

When two grams of calcium carbonate are heated in a closed 4 L vessel, the following equilibrium is achieved:
CaCO3(s) ->

A

2.68 * 10^-3

10
Q

In a reaction, gaseous reactants react to give gaseous products. How is the concentration of the reactants and products related to their pressures?

A

directly

11
Q

At 20 degrees C, the vapor pressure of water is 0.0231 atm. What are the values of Kp and Kc for this process?
H2O(l) ->

A

Kp = 0.0231 and Kc = 9.6*10^-4

12
Q

For the following reaction, 4NH3(g) + 3O2(g) -> 2N2(g) + 6H2O(g), what is the value of delta n?

A

1

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