1. Drill – 5/17/11
Calculate the pH of an aqueous solution that contains 5.00 g of HNO3 in 2.00 L of solution.
What would the pOH be?

2. Titrations

3. Acid-base indicators are…
Compounds whose color is sensitive to pH.
Indicators are either weak acids or weak bases.
For example, weak acid indicators will lose a proton in a base. The deprotonated version displays a different color.

4. Measuring pH
pH paper is a universal indicator. It is made by soaking the paper in several different indicators.
A pH meter measures the voltage between two electrodes. The voltage is measured based on the concentration of the hydronium ion.

5. Phenolphthalein
An indicator that changes color from clear in acid to pink in base (pH 8-10).
This is the indicator that we will use in the lab tomorrow!

7. Titrations
The controlled addition and measurement of the amount of a solution of known concentration required to react completely with a measured amount of a solution of unknown concentration.

9. Standard Solution
The solution that contains the precisely known concentration of a solute is known as a standard solution. The standard solution is often the titrant (it is titrated into the unknown solution)

10. Pg

11. Good color!
Too much base!

12. Titration Curve
A titration curve is drawn by plotting data attained during a titration, titrant volume on the x-axis and pH on the y-axis. The titration curve serves to profile the unknown solution.

13. Equivalence Point
The point at which the two solutions used in a titration are present in equal amounts (same number of moles of acid and base)
Amount of acid in moles = Amount of base in moles
*Note: this is not the same volume or the same concentration, just the same MOLES

14. Equivalence Point
Strong acid + strong base = equivalence point at pH of 7
Strong acid + weak base = equivalence point at pH of <7
Weak acid + strong base = equivalence point at pH of >7

15. If we know the molarity and the volume of acid used, then can we calculate the amount of moles of acid? How?
MolA = MAVA

16. How to solve titration problems:
Write the balanced neutralization equation
Solve for moles of given (using molarity and volume)
Convert from moles of given to moles of unknown using mole ratio
Use moles of unknown to solve for molarity or volume.
If moles are equivalent, then: MAVA =MBVB

17. Worksheet!

18. Green workbook, pg