Analysis Of Volumetric Analysis On Vinegar

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Vinegar is liquid with main component acetic acid (also known as ethanoic acid) and as well as some other chemicals compound. The estimation of the acetic acid concentration in a sample of vinegar was determined based on the stoichiometric reaction between sodium hydroxide (NaOH) and acetic acid that form sodium acetate (CH3COONa) and water (H2O) as follow. CH3COOH (aq) + NaOH (aq) CH3COONa (aq) + H2O (l) However, the method of volumetric analysis is highly dependent on a pure standard which the amount of substance present is accurately known. Prior to estimation of the acetic acid, sodium hydroxide (NaOH) was used as the standard solution. Thus, the concentration of the sodium hydroxide (NaOH) was first determined because sodium…show more content…
An acid-base indicator is a substance that undergoes a distinct colour change at or near the equivalence point. The point in the titration at which the colour change occurs is called as end point. Obviously, the titration will be accurate only if the end point and the equivalence point coincide fairly closely. For this reason, an acid-base indicator used in this acid-base titration must be selected carefully in order to obtain an accurate result. Thus, the acid-base indicator used in this experiment is the phenolphthalein. Besides, phenolphthalein is also a suitable indicator for titration between a strong base and a weak acid. Phenolphthalein is colourless in an acid solution but pink in base solution. Phenolphthalein was added into both original oxalic acid (C2H2O4) and acetic acid (CH3COO) solution before the acid-base titration was carried out. Phenolphthalein is a weak acid and is represent as Hln in the following chemical…show more content…
In acid-base chemistry, the solution concentration is expressed in normality (N or CN). Normality is defined as number of equivalent weights of solute that dissolved in per liter of solution. As a practical matter, normality closely resembles with molarity or moles per liter. Therefore, scientific textbooks typically define the normality of an acid or base as “equivalents per liter”. Normality is used in place of molarity as mostly 1 mole of acid does not neutralize with 1 mole of base. Most of the chemists prefer to express the concentration of acids and bases in normality as to have a one-to-one relationship between acids and bases. In monoprotic acid and monoprotic base such hydrochloric acid (HCl), hydrogen bromide acid (HBr), sodium hydroxide (NaOH) and potassium hydroxide (KOH), its normality is equal to the molarity (N=M). This is because monoprotic acid and base have 1 equivalent hydrogen ion (H+) and hydroxide ion (OH-) respectively per liter of solution. Meanwhile, for diprotic acid and base such as calcium hydroxide, Ca(OH)2 and sulphuric acid, H2SO4, its normality is equal to twice the molarity (N=2M). This is due to diprotic acid and base have 2 equivalent hydrogen ion (H+) and hydroxide ion (OH-) respectively per liter of

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