Catalyst1. What is the difference between a strong base and a weak base?2. What does it mean for something to dissociate?3. What are the units of Molarity? What does Molarity mean?

End

Justify – TPS

• Why did the solution of NaOH change colors the way that it did once I mixed the two?

LECTURE 6.4 – ACID/BASE TITRATIONS

Today’s Learning Targets

• 6.6 – I can calculate the concentration of an unknown acidic solution using a titration.

Today’s Focus Question• I have my acid that I need to dispose of

my body with, but how do I know the concentration so as to ensure it is strong enough to dissolve everything?

What are indicators?

I. Acid/Base Indicators• Indicators – Some compounds change

color depending on pH.• Therefore, these compounds tell us the

general pH of our solution based their color

How are indicators used in titrations?

I. Titrations• Often times, we have

solutions of unknown concentrations

• Titration – The controlled addition of solution of known concentration/volume to a solution of known volume, but unknown concentration.

Acid/Base of known volume and unknown concentration with an indicator.

Acid/Base of known volume and concentration.

II. Equivalence Point• Equivalence Point – The

point at which the two solutions used in a titration are present in equal amounts.

• We use indicators to spot this point

• For this class, always at pH = 7

• Moles of acid = moles of base at this point

How are titrations used to calculate concentrations?

I. Calculating Concentration for Titrations

Volume of base that was added in titration

Molarity of base

Volume of unknown acid

Mole Ratio from balanced chemical reaction

Class Example

• If it takes 0.540 L of 0.1 M NaOH to neutralize 0.125 L of an HCl solution, what is the concentration of the HCl?

Class Example

• If it takes 0.140 L of 0.051 M HNO3 to neutralize 0.225 L of an LiOH solution, what is the concentration of the HNO3?

Table Talk• It takes 2.540 L of 1.1 M HBr to neutralize 1.25 L

of an KOH solution, what is the concentration of the HBr?

Quiz

• You have 15 minutes to complete this quiz.

Around the World

• There are 6 questions for you to try around the room.

SUMMARIZE

Closing Time• Worksheet 6.3 is due on Thursday/Friday