Le Chatelier's Principle (Concentration & Pressure)

Le Chatelier's Principle states that if a chemical system at equilibrium is disturbed,

• the system will adjust to increase the effect of the disturbance.

• the system will adjust to reduce the effect of the disturbance.

• the system will not adjust.

For the reaction...

N_2(g) + O_2(g) <−> 2NO_(g)

If O_2(g) is removed, the concentration of N₂ will _______.

• increase.

• decrease.

• remain the same.

• double.

For the reaction...

N_{2 (g)} + 3 H_2(g) <−> 2 NH_{3 (g)}

If the pressure in the system is increased, the reaction will __________________.

• shift to the left

• shift to the right

• not shift

The three factors that affect the equilibrium of a reaction are temperature, pressure and __________.

• energy

• enthalpy

• concentration

• ice

For the reaction,

2SO₂ (g) + O₂ (g) ⇌ 2SO₃ (g)

Removing O₂ (g) will cause the equilibrium position to

• shift to the left.

• shift to the right.

• not shift.

For the reaction...

SO₂ (g) + O₂ (g) <−> SO₃ (g)

If the concentration of SO₂ (g) is increased, the equilibrium of the reaction will ___________.

• shift to the left

• shift to the right

• not shift

If I add a chemical to a system at equilibrium, increasing its concentration,

• the reaction will not shift.

• byproducts (other unwanted chemicals) will be formed to use the excess.

• the reaction will shift to the same side of the equation where it appears to make more of it.

• the reaction will shift to the opposite side of the equation where it appears to use some of it up.

Increasing the pressure on an equilibrium system will

• shift the reaction to the side with more moles of chemicals

• shift the reaction to the side with more moles of gas

• shift the reaction to the side with fewer moles of gas

• shift the reaction to the side with fewer moles of chemicals

Tags

NGSS.HS-PS1-6

Consider the following reaction:

Fe³⁺ + SCN^- ↔ FeSCN ²⁺

(Light Yellow) (Deep Red)

Adding Fe³⁺ produced the following change in the equilibrium:

• The color in the test tube became a deeper red color because the equilibrium shifted to make more reactants.

• The color in the test tube became a deeper red color because the equilibrium shifted to make more products.

• The color in the test tube became a lighter color because the equilibrium shifted to make more reactants.

• The color in the test tube became a lighter color because the equilibrium shifted to make more products.

Consider the following reaction:

Fe³⁺ + SCN^- ↔ FeSCN²⁺

(Light Yellow) (Deep Red)

Adding AgNO₃ to the test tube removed SCN ^- from the reaction, causing the reaction to

• produce more reactants and decrease the amount of products.

• decrease the amount of products causing a deeper color.

• produce a deeper red color because the production of more reactants.