Marisol Camacho AP Chemistry Per. 1-2 10/31/12 Titration Lab Titrations are a very useful method of discovering the amount or concentration of unknown substances. The method is very well suited towards acid-base reactions. Titrations are often used in industry to analyze products to be sold. In this lab, standardizations will be done in the first two experiments and then titration analysis in the third. Standardization of a base (NaOH) using a primary standard (KHP) Standardization of an acid (HCL) with the standard base
Titration analysis of unknown acids and bases (antacid tablets) Standardization of NaOH Materials: -Buret -250 mL Erlenmeyer flask -0. 1 M NaOH -0. 8 g KHP -Water -Three 150 mL beakers -magnetic stirrer A buret was rinsed with water and then with a small amount of the NaOH solution. Then the buret was filled with NaOH. The initial volume was read and recorded and the buret was labeled as BASE. Then approximately 0. 8 g of KHP was placed in the flask. 100 mL of water was added and was swirled until dissolved. Three drops of phenolphthalein indicator were then added.
The mixture was then placed on the magnetic stirrer and drops of the base solution (NaOH) were added through the buret until it turned a very faint pink. The final buret volume was then read and recorded. Data | Trial 1 |Trial 2 | |Mass of KHP in flask |85. 2 |84. 8 | |Initial buret reading |48mL |50mL | |Final buret reading |18. 5mL |18. 4mL | |Volume of NaOH required to neutralized the KHP |30. 5mL |31. 6mL | | Calculations: II. Standardization of HCL solution Materials: -Buret -250 mL Erlenmeyer flask -0. 1 M HCL -0. 1 M NaOH -Water Three 150 mL beakers -magnetic stirrer 50mL of 0. 1 M HCL was obtained in a beaker. A second buret was rinsed with water and then a small amount of HCL, and then filled with HCL. It was then labeled ACID. The initial volume was recorded and then approximately 10 mL was delivered into a flask. 100 mL of water and 3 drops of phenolphthalein indicator were added. The initial level was then read in the standard NaOH buret. The acid was then titrated to the faint pink endpoint with the NaOH The titration was then repeated with a second sample of HCL.
The calculated molarities of HCL should be within 1% of each other. Data |Trial 1 |Trial 2 | |Volume of acid sample |50mL |50mL | |Initial buret reading |50mL |50mL | |Final buret reading |39. 7mL |39. 8mL | |Volume of NaOH used |10. 3mL |10. 2mL | |Molarity of standard NaOH |0. 1M |0. 1M | | Calculations: III. Titration Analysis of Unknown Acids and Bases Materials: -antacid tablets -Buret -250 mL Erlenmeyer flask -0. 1 M HCL -0. 1 M NaOH -Water -Three 150 mL beakers -magnetic stirrer -methyl orange indicator 1. 1. An antacid tablet was obtained and massed.
It was then ground with a mortar and pestle. Two portions were then massed at 0. 6-0. 7 g each. 2. 2. The samples were then added to two 250mL flasks. From the acid buret, 60mL of the HCL was added to the powder. It was swirled until it was mostly dissolved. 3. 3. 4-5 drops of methyl orange indicator were added to the sample flask. The solution should have turned pink-red. 4. 4. This has neutralized a portion of the acid. It is our job to figure out how much HCL was neutralized by titrating the leftover acid with our the standard base (NaOH).
The acid is back titrated, and as the endpoint is reached the NaOH is added drop by drop. The endpoint of the titration is when the acid has a full color change. 5. 5. It was then repeated with the other antacid sample. Data |Trial 1 |Trial 2 | |Mass of whole antacid tablet |1. 27g |1. 29g | |Mass of antacid sample |0. 65g |0. 7g | |Volume of HCL added |60mL |60mL | |Molarity of Standard HCL |0. 1M |0. 1M | |Initial buret reading of NaOH |49. 5mL |50mL | |Final buret reading of NaOH |32. 5mL |31mL | |Volume of NaOH required |17mL |19mL | |Molarity of Standard NaOH |0. 1M |0. 1M | | Calculations: