Chapter #16

Acid-Base Titration and pH

Chapter 16.1

• In the self-ionization of water, two water molecules produce a hydronium ion and a hydroxide ion by transfer of a proton.

• Kw= H3O+ OH-

• Kw= 1.0 X 10 -14 M2

• The pH of a solution is defined as the negative of the common logarithm of the hydronium ion concentration.

• The pH scale 0-14. 7 is neutral…pH<7 acid…pH>7 base

• pH= -log ( H3O+)

Chapter 16.2

• Acid-base indicators are compounds whose colors are sensitive to pH.

• pH range over which an indicator changes color is called its transition interval.

• pH meter determines the pH of a solution by measuring the voltage between the two electrodes that are placed in the solution.

• Titration is 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 concentrations.

• Equivalence point is the point at which the two solutions used in a titration are present in chemically equivalent amounts.

• End point is the point in a titration at which an indicator changes color.

Titration Problems

1. Balance equation

2. Use the known solution to figure out the number of moles (M=mol/L)

3. Use the mole to mole ratio to figure out the moles of the unknown.

4. Determine the Molarity of the unknown using the given volume

• “Flask”. May 7, 2007. http://www.chem.ualberta.ca/~iip/chem211irc/TotalSalt(start).jpg

• “Let’s Titrate”. May 7, 2007. http://genchem.rutgers.edu/aanimate.gif

• “Titration curve”. May 7, 2007. http://www.cofc.edu/~kinard/Applets/WeakAcidTitration.gif