PH Titration Lab Report Example | Topics and Well Written Essays - 1500 words

PH Titration - Lab Report ExampleThe paper describes the experiment. During titration, it is essential to figure out the equivalence even out where seawalles of acid and moles of base added expire equivalent. To aid an experimenter in this situation, a halochromic organic compound known as indicator (s.a. phenolphthalein, methyl red, methyl orange, and bromothymol blue) is incorporated where appearance of color change from candid solution signifies the end point or the point assumed to be nearest the point of equivalence. At this stage, the volume of reading from the burette is noted win the instant the indicator changes color. With experimental outcomes comprising known molar concentrations and volumes of acid and base used, pH is calculated. In place of an indicator, glass electrode is utilized so that multiple pHs may be read and graphed from which to determine the pH at the equivalence point. For the neutralization reaction occurring between HCl (aq) and NaOH (aq) For the n eutralization reaction occurring between CH3COOH (aq) and NaOH (aq) Hypothesis The equivalence point is achieved once the titration has gone to the extent when the acid (analyte) and the base (titrant) are in equimolar amounts which takes place on yielding a neutral pH along a steep region in the titration yield Aim To locate the equivalence point through the measure of pH based on the titrant volume vs. pH-titration curve obtained in the experiment and identify the remaining species (in excess) as well as find the pH of the resulting solution after each titration attempt Method The burette was filled with 1.0 NaOH to the zero mark. A 250- conical flask was rinsed with distilled pee, emptying the flask and refilling it with about 50 of deionised water, after which, a 25 of 0.1 HCl was poured into the flask via pipet and the flask was placed on the magnetic scaremonger. With the stirrer bar dropped in the flask, the glass electrode was immersed in the flask then the burette was po sitioned over the flasks mouth such that the NaOH would be added into it without obstruction from the glass electrode. The magnetic stirrer was turned on and the flask was adjusted in the manner that would enable the stirrer bar to move freely, having no obstructive contact with the glass electrode throughout the titration process. Measuring of the pH prior to titration was initiated then successive additions of the base titrant were carried out starting with 1 until the equivalent point was arrived at, followed by 0.2-additions that sum up to approximately 8 of NaOH. Final addition of two consecutive 1- titrant amounts was made, taking into account the pH reading for each addition from the onset of titration to this point. Another trial (using the same analyte -- HCl) was performed, then titration was repeated, this time using a different analyte (0.1 CH3COOH) and applying the same quantity (50 ) of deionised water and of 1.0 NaOH. As conducted for HCl, pHs of neutralization react ion between HOAc (analyte) and the titrant (NaOH) were correspondingly read after each base addition. Results and calculations Note ( 1 cm3 ? 1 mL 1 mol / dm3 ? 1 M ) pH equivalence point is about 6.8 based on the graph. This corresponds to NaOH volume of about 5.5 mL. mmoles NaOH = (1.0 M) (9.00 mL) = 9.0 mmoles NaOH mmoles HCl = (0.1 M) (25.00 mL) = 2.5 mmoles HCl Upon neutralization, 9.00 mmoles - 2.5 mmoles = 6.5 mmoles NaOH left total volume = 50 + 25 + 9 = 84 mL OH- = = 0.07738 M ---? pOH = -log (0.07738) pOH = 1.11 so that pH = 14 - 1.11 ---? pH = 12.89 Since NaOH and HCl are strong base and strong acid, respectively, pH