Aim: How can we use titration to find the strength of a solution? Do Now: 1.Take out a calculator and reference tables. 2.Write a neutralization reaction for the following acid and base: HBr, and KOH. 3. Label the acid, base, water, and salt. 4. Write the net ionic formula for this reaction.

Answer to do now:

Reminder- How much of an acid or base is needed to neutralize a base or acid? Example: A water solution contains 2 moles of HCl. How much Mg(OH) 2 should be added to exactly neutralize it? What does it mean that the reaction is neutralized? Neutralization occurs when the same number of H + ions are in the solution as OH - ions.

How can we use this information? We can use this information to calculate the concentration of an unknown solution using the process called titration. During titration, an acid/base with a known concentration is added to a base/acid of unknown concentration until neutralization occurs. How can we tell when neutralization has occurred? We use an indicator such as phenolphthalein which is a very weak acid that will turn pink when it is neutralized by a base. The volumes of both the concentrated solution (aka the standard solution) and the unknown solution are measured.

The titration formula We can calculate the concentration of the unknown solution using the formula: (check Table T)

A practice problem Example: How many mililiters of 4.00 M NaOH are required to exactly neutralize 50.0 mililiters of a 2.00 M solution of HNO 3 ?

Another Practice Problem What is the molarity of an HCl solution if 20mL of the acid is needed to neutralize 10mL of a 0.5M NaOH solution?

One More Problem What is the concentration of a sulfuric acid solution if 50mL of a 0.25M KOH are needed to neutralize 20mL of the H 2 SO 4 solution of unknown concentration?

Activity/Homework Activity – Regents questions on back of sheet. HW # - Review Book Page 185 #40-57 odd OR even