Buffer and Solution Preparation


 

AIM 

The aim of this experiment concluded of the preparation of some specific buffers by using the Handerson-Hasselbach`s equation and some solutions, such as glucose and SDS. Additionally, the arrangement of pH values of the buffers by adding either a certain base or acid and the glucose/SDS solutions by adding distilled water was aimed in that experiment.  

 DISCUSSION 

 In this experiment, we’ve aimed the preparation of buffers including Z and pH7 phosphate buffer and other solutions including glucose and SDS solutions which are used in various biological processes. We’ve understood that the meaning of buffer and solutions. Buffer solution is the aqueous solution which composed of a mixture of a weak acid and its conjugate base or inversely and used to keep the pH level at an approximately constant value for usage in various applications. Also the 4th group used the Handerson-Hasselbalch Equation method with Na2HPO4 and NaH2PO4 and according to equation between these chemicals which gave below: 

H2PO4 ↔H+ + HPO4 

They calculated the molarity of H2PO4 and HPOby using a formula as pH= pKa + log [conjugate base] / [acid] and so they calculated the amount of each chemical which will be used. Thereby, we’ve learned the applying the Handerson-Hasselbalch Equation method. Actually, we’ve referred as the pH of a solution is based on the concentration of H3O+ ions which are present in the solutions and so weak acids don’t completely dissociate into ions, when they react with water. This case can change different weak acids. In addition to this, the Handerson-Hasselbalch Equation shows us the balance pH calculation of a solution including weak acid and its conjugate base which is given below equation : 

pH = pKa + log ([base])/([acid]) 

According to this equation, pKa is referred as the weak acid’s ionization meaning that dissociation of weak acids into ions even including the H3O+ ions. So the Handerson-Hasselbalch Equation is a common method which used in preparation of buffers for usage in the several laboratory applications. The reason of adding the HCl into the buffer was to decrease the pH value. If we could added the NaOH instead of HCl into the buffer, gradually, the pH value could be larger than 6 because of increasing the OH- ions in the buffer. For the pH 8 Z buffer, we’ve measured the first value lower than 8 and so we’ve tried to increase this value until pH 8 by adding NaOH basic solution slowly. The reason of adding the NaOH into the buffer was to increase the pH value. If we could added the HCl instead of NaOH into the buffer, gradually, the pH value could be lower than the first measured pH value because of increasing the H+ ions in the buffer. The reason of this can be mistakes in weighing of the chemicals or not completely dissociation of ions, so the weak acid for this buffer may not be dissociated into its ions completely. Temperature is another factor that affects the ionizations, because when the temperatures increase, chemicals`s ionizations increase, leading thus to a decrease in the pH values. Additionally, the amount of dioxide carbon which is dissolved on the water affects in the lowering of pH as it causes acidification.  

 

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