Catalyst 3/21/14

• On your Catalyst Sheet, please answer the following questions:

1. How does a catalyst speed up a reaction?2. Scenario: You have 6 rocks on one side of a

scale and 2 rocks on the other side. The rocks are equal size. Is this scale balanced?

3. How can you restore balance to this scale without removing or adding any rocks to the scale?

• When you are done, raise your hand quietly for a stamp.

Catalyst 3/21/14

• On your Catalyst Sheet, please answer the following questions:

A + 3B 2C + D + heat

1. If you add more C to the system, which way will the reaction shift?

2. If you decrease temperature, which way will the reaction shift?

3. If all molecules are gaseous and you decrease pressure, which direction will the reaction shift?

• When you are done, raise your hand quietly for a stamp.

Announcements

• Homework: 8.5 Le Chatelier’s Principle (Period 2 only)

• Homework: Benchmark 3 Study Guide• Lab Report deadline delayed to Saturday

on Google Drive by noon (12 pm)• If you absolutely cannot use Google Drive,

talk to me before you email your lab report to me at kpan@luskinacademy.net

• Questions? Shoot me an email or talk to me during tutoring today.

Pass Up HW

• Pass Up 8.5 HW: Le Chatelier’s Principle

LECTURE 8.5 – LE CHATELIER’S PRINCIPLE

Today’s Learning Target

• LT 8.6 – I can define Le Chatelier’s principle and use this principle to predict how concentration, temperature, and pressure will impact a given equilibrium.

What is Le Chatelier’s Principle?

I. Le Chatelier’s Principle • If a system at

equilibrium is disturbed, it will shift to restore its equilibrium

• Systems can be disturbed by changes in concentration, pressure, and temperature

How do concentration, pressure, and temperature impact

equilibrium?

I. Le Chatelier’s & Concentration

• The equilibrium will shift away from whatever side increases in concentration

• The equilibrium will shift toward whatever side decreases in concentration

Video: Le Chatelier’s & Concentration

Class Example

• I have the following equilibrium:H2O ⇌ H3O+ + OH-

• If I add H3O+, then will my reaction shift to the right or to the left?

Another Example

• I have the following equilibrium:CaCO3 ⇌ CaO + CO2

• If I remove CaCO3 from the system, then will my reaction shift to the right or to the left?

II. Le Chatelier’s & Temperature

• Heat (in kJ or J) can be listed as a reactant or product

Heat + Reactants ProductsReactants Products + Heat

• Increasing temperature will shift the reaction away from the heat

• Decreasing temperature will shift it toward the side with heat

Example

• I have the following equilibrium:N2 (g) + 3H2 (g) ⇌ 2NH3 (g) + 92 kJ

• If I increase the temperature, then will my reaction shift to the right or to the left?

Another Example

• I have the following equilibrium:556 kJ + CaCO3 (s) ⇌ CaO (s) + CO2

(g)• If I decrease the temperature, then

will my reaction shift to the right or to the left?

III. Le Chatelier’s & Volume/Pressure

• Only matters when gases are involved (g)

• Increasing pressure shifts the reaction to the side with fewer molecules

• Decreasing pressure shifts the reaction to the side with more molecules

LESS PRESSURE4 MOLECULES

MORE PRESSURE2 MOLECULES

Video: Le Chatelier’s & Pressure

Class Example

• I have the following equilibrium:N2 (g) + 3H2 (g) ⇌ 2NH3 (g)

• If I increase the pressure, then will my reaction shift to the right or to the left?

White Board Questions

• State whether it will shift to the left, right, or stay the same based on the given conditions

NaOH (aq) + HCl (aq) NaCl (s) + H2O (l)

(1)Add HCl(2)Remove NaOH(3)Add NaCl(4)React NaOH with HNO3

White Board Questions

• State whether it will shift to the left, right, or stay the same based on the given conditions

4HCl (g) + O2 (g) 2H2O (g) + 2Cl2 (g) + 113 kJ

(1)Increase pressure (2)Decrease temperature(3)Add H2O

(4)Remove O2

(5)Add HCl

White Board Questions

• State whether it will shift to the left, right, or stay the same based on the given conditionsNaCl (aq) Na+ (aq) + Cl- (aq) + 426 kJ

(1)Decrease the temperature (2)Add Na+

(3)Remove Cl-

(4)Add HCl (think about what the compound contains)

Benchmark 3 Study Guide

Period 2

• Goal: Complete at least half of Benchmark 3 Study Guide today

Period 4• Goal: Complete

Benchmark 3 Study Guide by today

• There are also laptops if you would like to work on your lab report before it is due tomorrow.

Extra Credit

• Textbook• Read p. 512-516• Answer 521-522 #7, 18-20