Aim How can we use titration to find
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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 Na. OH 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 20 m. L of the acid is needed to neutralize 10 m. L of a 0. 5 M Na. OH solution?
One More Problem What is the concentration of a sulfuric acid solution if 50 m. L of a 0. 25 M KOH are needed to neutralize 20 m. L 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
