Chemistry 30 Equilibrium

The pressure on each of the following systems is increased by decreasing the volume of the container. Explain whether each system would shift in the forward direction, the reverse direction, or stay the same.

a.	2 SO_{2 (g)} + O_{2 (g)} 2 SO_{3 (g)}
	forward reaction is favored; there are fewer moles of gas on the product side.

b.	H_{2 (g)} + I_{2 (g)} 2 HI_(g)
	No change - same number of moles on each side.

c.	CaCO_{3 (s)} CaO_(s) + CO_{2 (g)}
	The reverse reaction is favored; there are no moles of gas on the reactants side vs. one mole of gas on the product side.

d.	AgCl_(s) Ag¹⁺_(aq) + Cl^1-_(aq)
	No change - no gases are present.

List three ways that the following equilibrium reaction could be forced to shift to the right:

2 NO_{2 (g)} 2 NO_(g) + O_{2 (g)}

Solution:

add more NO_{2 (g)}
remove NO_(g) or O_{2 (g)}
decrease the pressure
increase the volume

Given the following equilibrium reaction:

2 C_(s) + O_{2 (g)} 2 CO_(g)

what will be the effect of the following disturbances to the system:

a.	adding CO (at constant volume and temperature)
	reverse reaction is favored. Adding a substance on one side of the equation forces the reaction to the other side of the equation.

b.	addition of O₂ (at constant volume and temperature)
	The forward reaction is favored to use up the additional O₂.

c.	addition of solid carbon (at constant temperature)
	No effect. Adding more of a solid does not change its concentration. The reaction may go on longer, but equilibrium is not affected.

d.	decreasing the volume of the container
	Count moles of GAS on both sides of the equation. There is 1 mole of gas on the reactant side, and 2 moles on the product side. Decreasing volume will favor the side with the fewest moles of gas - the reverse reaction will be favored.

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Chemistry 30

Chemical Equilibrium

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