University:
High School
Course:
High School Chemistry
Academic year:

2023
Views:

10

Pages:

2
Author:

D Lathiya

EXPERIMENT NO - 14 Aim: Preparation of carbonate-bicarbonate buffer of pH 10.2. Requirements: (a) Glasswares: Flask, Pipette, Stir rod. (b) Chemicals: Sodium carbonate, Sodium bicarbonate, Distilled water. Reagent Preparation: Sodium carbonate solution 0.2M: Dissolve 2.12 gm of anhydrous sodium carbonate in 100 mL distilled water. Sodium bicarbonate solution: Dissolve 1.68 gm of sodium bicarbonate in 100 mL of distilled water. Principle: Buffer is a solution that resists the change in its pH due to slight dilution or due to addition of small amounts of acids or bases. There are two main types of buffers: Acidic buffer that is a mixture of weak acid and its salt with strong base, for example, acetic acid-sodium acetate buffer. Basic buffer that is a mixture of weak base and its salt with strong acid, for example, ammonium hydroxide-ammonium chloride buffer. The pH of the buffer solution can be calculated using Henderson's equation pH = pKa + log ([Salt] / [Acid]) Here Ka is the dissociation constant of the acid and pKa = -log Ka. Procedure: Pipette out exactly 27.5 mL of sodium carbonate (Na₂CO₃) solution. To this add 22.5 mL of sodium bicarbonate solution and made upto 100 mL with distilled water which corresponds to 0.2 M sodium carbonate and bicarbonate buffer. Standardise pH meter and measure the pH of required buffer. This gives the Carbonate-bicarbonate buffer pH 10.2. Result: Carbonate bicarbonate buffer was prepared and pH observed was 7.5 which was adjusted to 10.2 using 1N HCl and 5N NaOH. Salivary Amylase Human salivary alpha amylase (HSAmy) is an important enzyme found in the oral cavity. It belongs to the glycoside hydrolase family and exists in various isoforms in salivary secretions. Humans produce two kinds of alpha amylase (salivary and pancreatic amylase) that overall share about 97% homology. HSAmy is a type of hydrolase that breaks down complex carbohydrates into simple sugars, like glucose or maltose, by cleaving α-1,4-glucosidic bonds. Further breakdown of the starch is completed by pancreatic amylase later in digestion. This enzyme has distinct components including a calcium ion, chloride ion, and various amino acid residues that play critical roles in hydrolytic activity and substrate binding. HSAmy can also bind to oral streptococci bacteria. This results in the bacteria either being removed from or stored in the oral cavity. Storage and accumulation of the bacteria in the oral cavity causes dental complications like plaque and tooth decay.