Experiment To Discover Buffering Region Of Histidine Monohydrochloride Biology

Table of Content


The purpose of this experiment is to analyze the consequence of temperature on the pH of a buffer. This can be done by detecting the alterations in pH of two different buffers when temperature of the buffer solution decreases from room temperature to 4A°C. pH of the buffers that are used to keep the pH of the lab samples can alter during alterations in temperature due to chilling procedure. Changes in pH of buffers upon temperature alterations can be explained by the Le Chatelier ‘s Principle. The survey of the consequence of temperature on pH of a buffer is important in taking the right pH buffer that is able to demo minimal alterations in buffer pH, to keep the belongingss of the biological samples that requires specific pH environment.

Materials and Methods

We study the consequence of temperature on the pH of a buffer by utilizing two different buffers, 0.01M K phosphate buffer and 0.01M Tris-HCl. 3mL of each buffer solution were pipetted into two separate trial tubing. The initial pH values of the two buffers at room temperature are measured utilizing the pH metre and recorded. Subsequently, both trial tubings were placed into the ice box to chill to 4A°C. After 20 proceedingss, the trial tubing were taken out of the ice box and placed in an ice bath to keep the temperature of the buffer solutions at 4A°C. The pH of the cooled buffer solutions were measured once more and recorded to obtain the consequences as seen in Table 3. By measuring the pH alterations ( either addition or lessening ) and the extent of these alterations from the original pH value, we can detect the consequence of temperature on the pH of a buffer.

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Based on the experimental consequences, it is clear that temperature changes the pH of the buffer. Though this is non a complicated experiment, it is still subjected to experimental mistakes and can be improved by the undermentioned ways:

Merely two types of buffers, Tris-HCl and K phosphate buffer, were used in this experiment. The experiment was besides conducted at merely one temperature. Using several buffers over a scope of temperatures will let us to detect the pH of a assortment of buffers at different temperatures. In add-on, both buffers used in this experiment showed an addition in alkalinity. Hence, including more assortment of buffers will let us to measure which type of buffer has inclination to go more alkalic or acidic with the alterations in temperature.

This experiment was conducted without the usage of a thermometer, hence at that place was uncertainness in finding the temperature of the buffer solutions. It was assumed that by puting the trial tubing in the ice box for 20 proceedingss and so reassigning into an ice bath, the buffer solutions would be maintained at 4EsC. However, it is hard to keep ice baths at 4EsC for a long period of clip due to heat addition from the milieus.

Possible solution to understate mistake:

Keep a thermometer in the ice bath and systematically look into the temperature of the ice bath. Add in more ice when the ice thaws.

It was hard to place the end point of the experiment. Even after a long period of clip ( about 30 proceedingss ) , the pH reading shown on the pH metre still continued to increase easy. Hence, halting the experiment excessively early may ensue in an inaccurate pH reading.

Possible solution to understate mistake:

Since it is hard to place the end point of the experiment, it is possibly more logical to standardize the continuance of the experiment for both buffer solutions. For illustration, 30 proceedingss for each buffer solution.


From this experiment, it can be concluded that a lessening in temperature will do a alteration in pH of a buffer. However, the pH of the buffer does non ever increase when temperature decreases. This depends on whether the dissociation procedure is endothermal or exothermal. In the instance of an endothermal dissociation procedure, pH of the buffer will increase when temperature decreases. This can be explained by Le Chatelier ‘s Principle which states that the backward exothermal reaction will happen so as to antagonize the alteration. Hence, the Tris-HCl and K phosphate buffers become more alkalic as temperature decreases.

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Experiment To Discover Buffering Region Of Histidine Monohydrochloride Biology. (2017, Jul 13). Retrieved from


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