'Determination of Ka for a weak Acdi Essay\r'

' origination\r\nIn the experiment preformed the objective is to quantify a weak corrosive with a intemperate base. In a titration of a weak red-hot with a strong base the titrant is the strong base and the analyte is a weak mordant. The reaction that will occur is the take on transfer of protons from the weak acid to the hydroxide ion. The selective information gathered will be equal on the titration curve, a graph of the volume of titrant being the strong base plotted against the pH .The pH is an indicator of an acids strength. The titration curve can be used to reconcile the pKa. By reading the graph the equation flow can be found; which is the point where decent parts acid and base have reacted by knowing this the half-equivalence can be found pH=pKa.\r\nProcedure\r\nIn the experiment pH melodic theme will be used instead of a pH meter. The pH will be heady at the beginning and the end of the titration and the data board will be used to calculate the fair(a) val ues. A burette is a more absolute piece of glassw ar used to deliver the titrate; in the lab being performed disposable pipette will be used making it very(prenominal) important to consistently dispense the same sizing contrives. Before the titration the volume of a drop must(prenominal) be determined. A pipet is completely receive with distilled water. The average number of drops in a mL and the average bar of a mL represented by on drop is calculated and record. piddle is added drop by drop to a receive cylinder from a pipet at the first, fleck and third mL lines the water drops are save. The average number of drops are calculated per mL. The average of the quantity of a mL represented by a drop is also recorded.\r\nA data circuit card is set up to represent the trail averages. starting line 2.0 mL of unmapped acid is measured into graduated cylinder and so poured into a beaker the volume is the recorded. By using a toothpick a drop of acid is placed onto low porti on of pH paper, the pH level is recorded. One drop of the phenolphthalein indictor is added to the acid and the deform is recorded. The beaker is set on a white planing machine of paper before moving on. Next, a nearly in the 24-well plate is filled with NaOH solution and accordingly sucked up into an empty pipet. The pipet is the held vertically slow adding drop by drop the NaOH into the beaker of the unknown solution. Drops are added until a color change occurs, changing to a faint pink for at least 30 seconds. A plastic spoon is used to tint after the addition of separately drop. The number of drops of NaOH is recorded and the equivalence point is now determined. A drop of the acid is now transferred by toothpick to the high rove pH indicator strip. The pH level of the acid is recorded before titration. The contents of the beaker are poured work through the drain and all equipment is thoroughly cleaned. The above map is repeated twice more, all data is recorded to 4 dec imal places for each trail on the data table. The average of the 3 trails is calculated and data is recorded.\r\nAt the top of the pH column the unknown’s acid’s starting pH level before titration is entered. Next, the pH level of the acid after the titration, at its equivalence point is entered at the bottom of the pH column. The appropriate pH levels for each 2 drop interval is thence calculated, by subtracting the initial pH from the final pH and dividing the resulting contrariety by the number of rows minus 1. This number is then added to the previous pH value.\r\nA graph is then made, pH is plotted on the y axis vertebra and volume of NaOH added on the x axis. This represents the titration curve. The pH that corresponds with the equivalence point and half equivalence points are fixed and the pKa is determined for the unknown acid, pH=pKa. The Ka is determined by taking the inverse log of the pKa(10-pka).\r\n'