Experiment 5C and 5D

Experiment 5C and 5D - Titration of Monoprotic and Diprotic...

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Titration of Monoprotic and Diprotic Acids Glossary of terms Acid : Any compound that can donate a proton H A + H 2 O H 3 O + (aq) + A - Strong acids ionize 100%. The equilibrium lies to the right. Weak acids ionize <100%. The equilibrium is dependant on K a . K a = [H 3 O + ][A - ] [HA] Base : Any compound that can accept a proton. B + H 2 O OH - (aq) + BH + Strong bases ionize 100%. The equilibrium lies to the right. Weak bases ionize <100%. The equilibrium is dependant on K b . K b = [OH - ][BH + ] [B] pH Scale : allows scientists to represent acid/base concentrations in small numbers. pH represents [H 3 O + ] and pOH represents [OH - ]. pH = -log [H 3 O + ] pOH = -log [OH - ] pH + pOH = 14 Titration: a standard laboratory method of quantitative/chemical analysis which can be used to determine the concentration of a known analyte. Analyte: What you are titrating. Titrant : a reactant of known concentration (a standard solution) and volume is used to react with a measured quantity of analyte. Using a calibrated burette to add the titrant, it is possible to determine the exact amount that has been consumed when the endpoint is reached. Equivalence point: This is classically a point at which the number of moles of titrant is equal to the number of moles of analyte, or some multiple thereof (as in di- or tri- protic acids). In the classic strong acid-strong base titration the endpoint of a titration is when the pH of the reactant is just about equal to 7, and often when the solution permanently changes color due to an indicator. For weak acids and bases the equivalence point is NOT at a pH of 7.
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½ Volume to Equivalence Point pH at equiv. pt pH at ½ equiv. Pt pH = pKa Buffer: (or buffered solution) is a solution that is resistant to change in pH when small amounts of acid or base are added. These solutions contain a combination of both a weak acid(or base) and it’s conjugate. If a small amount of string acid(or base) is added to the buffer, most of the added H
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Experiment 5C and 5D - Titration of Monoprotic and Diprotic...

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