Synthesis of Salicylic Acid and Potentiometric Determination of Its Purity and Dissociation Constant

In this lab, the purpose was to determine the stability of a substance after adding an acid or a base. The results claim that liver and buffer are the most resistance to change in pH. Looking at figure 3, buffer and liver both maintain a stable pH even with the addition of an acid or base. However, potato and water have less buffer in them since their pHs did change. In figure 3, the potato acid’s pH level decreased by two, and the potato base’s pH level increased by two. The level of pH of a water acid decreased by 4, while the water base’s pH increased by 5. These results all tie to the fact that buffer is a substance that maintains a stable pH; the presence of buffer in organisms help maintain homeostasis by binding or releasing hydrogen

1. To titrate a hydrochloric acid solution of “unknown” concentration with standardized 0.5M sodium hydroxide.

Salicylic acid is also used in a variety of other personal care items such as dandruff shampoo, antiseptic and toothpaste. [2]

Salicylic acid was esterfied using acetic acid and sulfuric acid acting as a catalyst to produce acetylsalicylic acid and acetic acid. The phenol group that will attack the carbonyl carbon of the acetic anhydride is the –OH group that is directly attached to the benzene since it is more basic than the –OH group attached to the carbonyl group. This method of forming acetylsalicylic acid is an esterification reaction. Since this esterification reaction is not spontaneous, sulfuric acid was used as a catalyst to initiate the reaction. Sulfuric acid serves as the acid catalyst since its conjugate base is a strong deprotonating group that is necessary in order for this reaction to be reversible. The need for the strong conjugate base is the reason why other strong acids such as HCl is not used since its conjugate base Cl- is very weak compared to HSO3-. After the reaction was complete some unreacted acetic anhydride and salicylic acid was still be present in

9) Filter the ppt formed as result of step 7 from the newly acidic solution.

Abstract: One mixture of two unknown liquid compounds and one mixture of two unknown solid compounds were separated, isolated, purified, and characterized by boiling point. Two liquid unknowns were separated, isolated, and purified via simple distillation. Then, the process of an acid-base extraction and washing were used to separate two unknown compounds into two crude compounds: an organic acid and a neutral organic compound. Each crude compound was purified by recrystallization, resulting in a carboxylic acid (RCO2H) and a pure organic compound (RZ). The resulting mass of the pure carboxylic acid was 1.688g with a percent recovery of 31.80%, the boiling range was 244-245 °C, and its density was 2.0879g/mL. The resulting mass of the pure organic solid was 2.4902g with a percent recovery of 46.91%, the boiling range was 52.0-53.4°C, and its density was 1.5956 g/mL.

We only added a small amount of HCl to the water and sodium chloride. We did not continue to add more HCl after a significant drop in pH was recorded. We added a total of 2 mL of HCl to both H20 and NaCl before the pH changed. The 1 gram solution of sodium acetate and acetic acid changed after a 8 mL, and the other two never dropped before we reached our total of 10 mL HCl.

In this experiment, the Fischer Esterification of an unknown acid and an unknown alcohol was used to prepare an unknown ester. Sulfuric acid was used as a catalyst in the reaction which then was put under reflux. After cooling, the pH of the solution was raised to approximately 8 using sodium carbonate. Diethyl ether was added, then the aqueous layer was removed and the organic layer was washed with sodium chloride. The aqueous layer was removed again and sodium sulfate was added. The unknown product was then identified using gas chromatography (GC) to obtain the retention time.

Acids differ considerable as to their strength. The difference between weak and strong acids can be as much as 10 orders of magnitude. Strong acids dissociate more completely than weak acids, meaning they produce higher concentrations of the conjugate base anion (A-) and the hydronium cation (H30+) in solution.

2. In Part I of this experiment, acetic acid is titrated with NaOH. The net ionic equation for acetic acid reacting with NaOH is CH3COOH+ NaOH =NaC2H3O2+H2O. The equivalence point is when the moles of the titrant and other solution are equal.. You detect the equivalence point by obtaining the point on the graph where the steep pH occurs. In titrating acetic acid with NaOH, the pH is greater than 7 at the equivalence point because NaOH is a strong base so it results in a higher pH, due to the OH- ions in the solution.

We will observe the reaction of a buffer solution with added acids or bases. We will then evaluate buffering capacity in response to additions added from dilute acid and bases to the buffer.

Within an acid-base titration the titration curve resembles the strengths of the corresponding acids and bases. A strong acid will correspond with a weak conjugate base, and a weak conjugate acid will correspond with a strong base. This is based on the Bronsted-Lowry model. The weak acid will donate protons to the hydroxide ion. Weak acids will have a low Ka value, the Ka value is the tendency of the acid to dissociate:

Using Graph 1: The Volume of Titrant Added in order to reach the Endpoint and the Corresponding pH Values, observe the vertical line of each titration and see the points in which the horizontal lines intersect it. These points give the

In this experiment were used three separation techniques: extraction, sublimation and recrystallization. During the first method, 0.70 g sample of salicylic acid-naphthalene mixture was dissolved in 10 ml of diethyl ether. The solution was placed in a separatory funnel and 10 ml of saturated aqueous sodium bicarbonate solution was added to it. After the initial gas was

In this lab a acid-base indicator phenolphthalein was used to determine endpoint of a reaction HCl(aq) and KOH(aq). At the end point all of the HCl(aq) would have reacted with KOH(aq), and the pH becomes 7. The phenolphthalein would changed colours from colourless to pink indication when enough KOH(aq) was added. The purpose of numerous trials was to use the average volume of the 3 trials with similar measurements.