Applications of Titration Essays - Bases, Sodium Compounds

Applications of Titration Essays - Bases, Sodium Compounds Applications of Titration November 27, 2015 December 2, 2015 S. Raphael Introduction: The laboratory method used in this experiment is titration. Titration can be traced back to the start of volumetric analysis, in the late eighteenth century. The study of analytical chemistry began in France (Bandos, 2015). The first burette was made by Francois Antoine Henri Descroizilles, a French chemist and pharmacist (Rosenfeld, 1999). The field began to spread to other European countries. The first text that mentioned titration was published in 1855 in Germany. It was titled Lehrbuch der chemisch-analytischen Titrirmethode (Instructional Book of Titration Methods in Analytical Chemistry). Karl Freiderich Mohr, the author of the book, is also responsible for advancing the burette from an inefficient graduated cylinder-type instrument to a tool with a clamp at the bottom that is still used today (Bandos, 2015). Titration is a laboratory technique that is used to determine the concentration of solution by reacting the known volume of that solution with the measured volume of a sol ution with a known concentration (Haberer et al., 2011). To determine concentration, the equation for concentration in relation to moles and volume is used. C=n/V C= concentration in mol/l n= moles in mol V= volume in L (Ms. Raphael, SCH 3U1, November 29, 2015). Molarity (M) or molar concentration is the unit used for expressing the concentration of solutions. It is defined as the number of moles of solute per liter of solution (Chemteam.info, 2015). To be categorized as an acid according to Arrhenius Theory, the solution must be able to form hydrogen ions when dissolved in water. To be categorized as a base according to Arrhenius Theory, the solution must be able to form hydroxide ions when dissolved in water (France, 2015). To be categorized as an acid according to Bronsted-Lowry Theory, the solution must be able to donate a proton, a hydrogen ion, to a base. To be categorized as a base according to Bronsted-Lowry Theory, the solution must be able to receive a proton, a hydrogen ion, from an acid (Williams, 2015). In both theories the acid must be an aqueous solution, be able to neutralize a base, and have a pH of less than 7. As well as a base must be an aqueous solution, be able to neutralize a base, and have a pH of greater than 7 (Chemtutor.com, 2015). In a titration, one reagent, the titrant, is slowly added to another, the titrate. In titration, the titrant is the solution with the known concentration, the titrate is the solution with the unknown concentration (Dartmouth.edu, 2015). In the experiment the titrant, sodium hydroxide, was diluted with distilled water to create a 0.5mol/L NaOH solution. The amount of distilled water need to dilute the base was calculated using the formula for dilution, which was rearranged. C1V1=C2V2, rearranged to solve for V1, V1= C2V2/ C1 C1=original concentration of solution C2=final concentration of the solution V1=original volume of the solution V2=final volume of the solution (Ms. Raphael, SCH 3U1, November 29, 2015). As the reagents are added to one another, using a burette, a chemical stoichiometric reaction occurs until the limiting reagent is exhausted. An indicator is used to distinguish when this happens. A burette is a clear tube with volume markings along its length and a tap at the bottom. The indicator changes colour when the end-point has been reached, which is at the point of neutralization (Richards Fromm, 2015). In the experiment phenolphthalein was used as an indicator. Phenolphthalein is a commonly used indicator in titrations. It is an acid-base indicator which is colourless when in acid solution, and turns pink to red as the solution becomes more basic (Pubchem.ncbi.nlm.nih.gov, 2015). To determine the pH of the solution, the equation to solve for pH was used. pH=-log[H3O+] pH= acidity or alkalinity of solution [H3O+]= concentration of solution (Ms. Raphael, SCH 3U1, November 29, 2015). The purpose of titration is to find the point at which the moles of the standard solution is equal to the moles of the unknown solution, this is known as the equivalence point (Clark, 2015). The mole is an SI unit, Systme International d'Units, which measures the number of particles in a given substance. One mole is equal to 6.02 x 1023 atoms, or other appropriate units