{"id":146,"date":"2025-05-29T02:10:09","date_gmt":"2025-05-29T02:10:09","guid":{"rendered":"https:\/\/pressbooks.hccfl.edu\/introchemlabmanual\/?post_type=chapter&p=146"},"modified":"2026-03-24T16:56:40","modified_gmt":"2026-03-24T16:56:40","slug":"introduction-to-titrations","status":"web-only","type":"chapter","link":"https:\/\/pressbooks.hccfl.edu\/introchemlabmanual\/chapter\/introduction-to-titrations\/","title":{"raw":"Introduction to Titrations","rendered":"Introduction to Titrations"},"content":{"raw":"https:\/\/youtu.be\/qASviaJHrtA\r\n
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Learning Outcomes<\/p>\r\n\r\n<\/header>\r\n

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  • Apply the safety rules in the chemistry laboratory through proper and safe handling of chemicals and chemical equipment.<\/li>\r\n \t
  • Identify and use common equipment and measuring devices in the chemistry laboratory.<\/li>\r\n \t
  • Properly record experimental data including the precision appropriate to the measuring devices used.<\/li>\r\n \t
  • Properly make measurements of length, mass, volume, and temperature.<\/li>\r\n \t
  • Properly perform the technique of filtration, quantitative transfer of materials, pipetting and use of the Bunsen burner.<\/li>\r\n \t
  • Tabulate and graph experimental data.<\/li>\r\n \t
  • Apply the steps of the scientific method.<\/li>\r\n \t
  • Describe characteristics of different types of chemical reactions including acid\/base reactions and write balanced chemical equations.<\/li>\r\n \t
  • Apply mole relationships to chemical reactions.<\/li>\r\n<\/ul>\r\n<\/div>\r\n<\/div>\r\n

    Concentration tells us how much solute is present in a given amount of solution. Molarity (M) is the most common unit of concentration and is defined as:<\/p>\r\nM<\/mi>=<\/mo>moles\u00a0of\u00a0solute<\/mtext>liters\u00a0of\u00a0solution<\/mtext><\/mfrac><\/mrow>M = \\frac{\\text{moles of solute}}{\\text{liters of solution}}<\/annotation><\/semantics><\/math>\r\n

    A titration is a controlled chemical reaction used to determine the concentration of an unknown solution by reacting it with a known amount of another substance. In this lab, the base (NaOH) will be titrated against the acid (KHP).<\/p>\r\n

    KHP stands for potassium hydrogen phthalate, and its chemical formula is:\u00a0 \u00a0KHC8<\/sub>H4<\/sub>O4<\/sub><\/p>\r\n

    It is a solid, monoprotic acid, and serves as a primary standard because it is:<\/p>\r\n\r\n

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      Highly pure<\/p>\r\n<\/li>\r\n \t

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      Stable<\/p>\r\n<\/li>\r\n \t

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      Easily weighed<\/p>\r\n<\/li>\r\n<\/ul>\r\n

      The actual reaction between KHP and sodium hydroxide (NaOH) is:<\/p>\r\nKHC<\/mtext>8<\/mn><\/msub>H<\/mtext>4<\/mn><\/msub>O<\/mtext>4<\/mn><\/msub><\/mtext>(<\/mo>a<\/mi>q<\/mi>)<\/mo>+<\/mo>NaOH<\/mtext><\/mtext>(<\/mo>a<\/mi>q<\/mi>)<\/mo>\u2192<\/mo>KNaC<\/mtext>8<\/mn><\/msub>H<\/mtext>4<\/mn><\/msub>O<\/mtext>4<\/mn><\/msub><\/mtext>(<\/mo>a<\/mi>q<\/mi>)<\/mo>+<\/mo>H<\/mtext>2<\/mn><\/msub>O<\/mtext><\/mtext>(<\/mo>l<\/mi>)<\/mo><\/mrow><\/semantics><\/math>\r\n

      This reaction proceeds in a 1:1 molar ratio: one mole of KHP reacts with one mole of NaOH.<\/p>\r\n

      To visually detect when all the KHP has reacted, phenolphthalein is added to the solution. It is:<\/p>\r\n\r\n

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        Colorless in acidic solution<\/p>\r\n<\/li>\r\n \t

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        Turns pale pink in basic solution<\/p>\r\n<\/li>\r\n<\/ul>\r\n

        The moment the solution turns and remains faint pink, the endpoint of the titration has been reached. The equivalence point is the theoretical point where the moles of base = moles of acid. The endpoint is the visible color change caused by the indicator. In a properly done titration, these two points occur very close together.<\/p>\r\n\r\n

        Example Calculation<\/strong><\/h2>\r\n

        Given:<\/strong><\/h3>\r\n
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          Mass of KHP = 0.650 g<\/p>\r\n<\/li>\r\n \t

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          Volume of NaOH used = 31.00 mL (0.03100 L)<\/p>\r\n<\/li>\r\n \t

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          Molar mass of KHP = 204.22 g\/mol<\/p>\r\n<\/li>\r\n<\/ul>\r\n

          Step 1: Moles of KHP<\/strong><\/h3>\r\nmol\u00a0KHP<\/mtext>=<\/mo>0.650<\/mn><\/mtext>g<\/mtext><\/mrow>204.22<\/mn><\/mtext>g\/mol<\/mtext><\/mrow><\/mfrac>=<\/mo>0.00318<\/mn><\/mtext>mol<\/mtext><\/mrow><\/semantics><\/math>\r\n

          Step 2: Moles of NaOH (1:1 ratio)<\/strong><\/h3>\r\nmol\u00a0NaOH<\/mtext>=<\/mo>0.00318<\/mn><\/mtext>mol<\/mtext><\/mrow>\\text{mol NaOH} = 0.00318 \\, \\text{mol}<\/annotation><\/semantics><\/math>\r\n

          Step 3: Molarity of NaOH<\/strong><\/h3>\r\nM<\/mi>=<\/mo>0.00318<\/mn><\/mtext>mol<\/mtext><\/mrow>0.03100<\/mn><\/mtext>L<\/mtext><\/mrow><\/mfrac>=<\/mo>0.1026<\/mn><\/mtext>M<\/mtext><\/mrow>M = \\frac{0.00318 \\, \\text{mol}}{0.03100 \\, \\text{L}} = 0.1026 \\, \\text{M}<\/annotation><\/semantics><\/math>\r\n

          Through this titration procedure, we determine the true molarity of NaOH by reacting it with a known quantity of KHP, using phenolphthalein to visually identify the endpoint. This experiment demonstrates the importance of stoichiometry, careful technique, and quantitative analysis in chemistry.<\/p>","rendered":"