Volumetric and Vinegar Analysis
This report presents volumetric and vinegar analysis. In volumetric analysis three trials of a solution. The volumetric analysis was obtained through titration, and chemical analysis, which allowed the molar concentration of a strong acid to be assessed in a standardized solution. The Average molar concentration of NaOH is approximately 0.279mol/L.
Vinegar analysis was conducted with the help of three trials to determine the percent by mass of acetic acid in vinegar instead of a standardized solution. The unknown vinegar being utilized was “Shaggy”. The average percent by mass of CH3COOH “Shaggy” is 1.41%.
According to “Laboratory ...view middle of the document...
KHP is slightly acidic, and it is often used as a primary standard for acid-base titrations because it is solid and air-stable, making it easy to weigh accurately. It is not hygroscopic. It is also used as a primary standard for calibrating pH meters because, besides the properties just mentioned, its pH in solution is very stable. KHP dissociates completely in water, giving the potassium cation (K+) and hydrogen phthalate anion (HP− or Hphthalate−). As a weak acid hydrogen phthalate reacts reversibly with water to give hydronium (H3O+) and phthalate ions.
HP− + H2O P2− + H3O+
Volumetric analysis was used to determine the molar concentration of our strong acid. To come to a result, a primary standard was utilized. A primary standard – an accurate mass of a solid
substance is measured on a balance, dissolved in water and then reacted with the substance being analyzed (Beran, 133). *(Once the molar concentration of sodium hydroxide is calculated the solution is said to be standardized, and is referred to as secondary standard solution (Beran, 135)). Using a calculated mass of KHP, it was to be determined the amount that would be required of the sodium hydroxide solution to reach the stoichiometric point, allowing for the phenolphthalein to serve as the indicator (pink color change would occur and persist for longer than a 15-30second burst.)
According to “Laboratory Manual for Principles of General Chemistry”, vinegar analysis is used to determine the percent by mass of acetic acid in vinegar. Volumetric analysis was utilized again, which is a chemical analysis that is performed primarily with the aid of volumetric glassware. For this procedure, a measured mass of vinegar is titrated to the phenolphthalein stoichiometric endpoint with a measured volume of a standardized sodium hydroxide solution. Since the volume and molar concentration of the standardized sodium hydroxide solution is known, the moles of sodium hydroxide used for the analysis are also known (Beran, 143). This is conducted by a titration procedure. “Shaggy”, vinegar sample that was used to perform this procedure, phenolphthalein was added, standardized sodium hydroxide was added via titration to the receiving flask until the endpoint was reached and the indicator (phenolphthalein) turned a faint pink color for longer than a 15-30 second burst.
Materials and Methods
The materials utilized during these experiment were: KHP, NaOH solution, buret, buret holder/titration set-up, phenolphthalein as an indicator, piece of white paper, Erlenmeyer flasks, pipette, acetic acid, and funnel.
The procedure was followed from Experiment 9 and 10 (p. 133, 143), “Laboratory Manual for Principles of General Chemistry” except KHP (0.3g) was used instead of KHC8H4O4, only three trials were completed instead of the instructed four, and portion B was excluded from the experiment for volumetric analysis, the vinegar was laboratory made instead of the typical 5% acetic acid that...