Titrations - mL of H 2 SO 4 solution. What is the...

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Titrations A useful way to determine a solute's concentration in a solution is to react the solution with  a solute in another solution of known concentration. This is known as a  Titration . Titration: Experiment which determines the concentration of a solute (reactant) using its  reaction of known stoichiometry with another solution (reactant) of known  concentration. For example, if I have a solution of sulfuric acid,  H 2 SO 4   (aq) , but don't know its  concentration, then I can react it with a  NaOH solution of known concentration. 2 NaOH (aq)  + H 2 SO 4   (aq)    Na 2 SO 4   (aq)  + 2 H 2 O (l) In a titration the titrant is added dropwise until the reaction is complete. Equivalence Point: Point at which stoichiometrically equivalent quantities are brought together. 40.0 mL of 0.20 M  NaOH is needed to neutralize (reach equivalence point) for 20.0 
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Unformatted text preview: mL of H 2 SO 4 solution. What is the concentration of H 2 SO 4 solution? 2 NaOH + H 2 SO 4 Na 2 SO 4 + 2 H 2 O How do we know when the reaction is complete? We add a tiny amount of indicator to the analyte that will change color when the solution has excess titrant (e.g. excess OH-). For example, phenolphthalein molecules are colorless in neutral and acidic solutions, but are reddish purple in basic ( i.e. , excess OH-) solutions. Indicator: A material which (by changing colors or other means) signals that the equivalence point has been attained. End Point: When the indicator indicates that the equivalence point have been reached ( e.g. , changes color). Indicators need to be chosen carefully, so they don't change color too soon or too late....
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This note was uploaded on 11/22/2011 for the course CHEMISTRY CHM1025 taught by Professor Laurachoudry during the Fall '10 term at Broward College.

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Titrations - mL of H 2 SO 4 solution. What is the...

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