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Loose Ends from Bell Work. An acidic solution makes the color of pH paper turn ___________________, while a basic solution makes the color of pH paper turn ________________. The indicator _________________________ is used to study neutralizations of weak acids with strong bases. Red. Blue.
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Loose Ends from Bell Work • An acidic solution makes the color of pH paper turn ___________________, while a basic solution makes the color of pH paper turn ________________. • The indicator _________________________ is used to study neutralizations of weak acids with strong bases. Red Blue phenolphthalein
What is a titration? • An experiment used to determine the concentration of an unknown by using a known amount of a solution with a known molarity. • The most common use is determining concentrations of unknownacids.
Titration Terms • Equivalence Point – the point at which the two solutions used in the titration are present in chemicallyequivalent amounts. • Standard Solution – a solution of known concentration • Titrant – A solution of known concentration that is used to titrate a solution of unknown concentration
Finding a Suitable Indicator • Every indicator has a transitionrange, the pH range through which an indicator changes color • The indicator selected must change at the appropriate time during the titration. • The instant at which the indicator changes color is the endpoint of the titration. • If the proper indicator was selected, the endpoint and equivalencepoint will be the same.
Calculations • The most important relationship deals with molarity. • Remember M = n/V • Where M = concentration (mol/L), n = moles, and V = volume in L • The resulting formula: • #H+ Macid Vacid = #OH- Mbase Vbase
Examples • If 20.6 mL of 0.010 M aqueous HCl is required to titrate 30.0 mL of an aqueous solution of NaOH to the equivalence point, what is the molarity of the NaOH solution? • In the titration of 35.0 mL of drain cleaner that contains NaOH, 50.08 mL of 0.409 M H2SO4 must be added to reach the equivalence point. What is the concentration of the base of the cleaner?