Buffer Solutions And Dilution Report - Lab Experiment

Acid and Base

The Bronsted-Lowry Theory of acids and bases

An acid is a proton (hydrogen ion) donor.

A base is a proton (hydrogen ion) acceptor.

Definition of buffer?

The capacity of the buffer solutions depends upon two factors

How do buffer solutions work?

buffer concentration?

Acidic buffer solutions?

Alkaline buffer solutions?

pH meter?

Moles in solutions?

1.How would you make 10mL of a 1:10 dilution of a 1M NaCl solution?
2. What would the final concentration of NaCl be from 1a above?
3.How would you make 80mL of a 1:20   dilution of a 1M NaCl solution?
4.How would you make 50mL of a 1:25   dilutions of a 1M NaCl solution?

Preparation of Buffers

LABORATORY REPORT

The control of pH is an essential aspect in carrying out biochemistry experiments; this is because a certain pH is required for an experiment to be carried out. Buffers solutions refer to the aqueous solutions which consist a mixture of conjugated base and a weak base and their pH changes slightly when a small amount of strong base or acid is added to it, and they are used to control the pH of an experiment. The central focus for carrying out this experiment was to find out how the buffer solution reacts to the dilution in comparison to a non-buffered solution. To produce some standard buffers while ensuring that all the components are measured out accurately. The buffer solution with a pH less than 7 is referred to as acidic buffer solution. Acid buffers are known to contain a weak acid and one of its salt which in most cases is sodium salt. The Alkaline buffer solution I the buffer solution which has a pH which is greater than 7 and in most cases made of a weak acid and one of its salts

Buffers solutions refer to the aqueous solutions which consist a mixture of conjugated base and a weak base or vice versa. The pH of the buffer solution changes slightly when a small amount of strong base or acid is added to it, and they are used to control the pH of an experiment (Boyer, 2013, p. 45).

In most cases, the Buffer solutions acquire their resistance to the pH due to the presence of the availability of an equilibrium between the acid and its conjugate base. By adding some amount of a strong acid to the equilibrium of the mixture the weak acid and its conjugate base usually shift to the left.

The objectives for carrying out this experiment was to find out how the buffer solution reacts to the dilution in comparison to a non-buffered solution. To produce a number of standard buffers while ensuring that all the components are measured out accurately (Cserhati, 2017, p. 165).

The buffer solution with a pH less than 7 is referred to as acidic buffer solution. Acid buffers are known to contain a weak acid and one of its salt which in most cases is sodium salt. The Alkaline buffer solution I the buffer solution which has a pH which is greater than 7 and in most cases made of a weak acid and one of its salts. It is possible to change the pH of a buffer solution by altering the ratio of base or acid to the salt, or by selecting a different base or acid and one of its salts.

The Bronsted-Lowry Theory of Acids and Bases

The ratio of the salt to that of the base or acid. The capacity of the buffer is maximum when the ratio of the salt to the acid or the base is 1:1.

From the results which were obtained during the experiment, it was found out that the pH value for the Tris-HCl solution when the concentration was 0.1M the pH was 7.96 and when the solution was diluted further by add 90Ml of water to attain the concentration of 0.001M the pH was lowered to 7.92.

This report contains the following sections; aims and objectives where the reasons for carrying out the experiment are explained. The methodology which explains the procedures followed during the experiment. The materials sections which outline and explain the apparatus and materials used and how they were used. The results part which shows the data. The discussion which discusses and explains the findings of the experiment.

The objectives of conducting this lab session were to:

To determine how the buffer solutions react to the dilution in comparison to a non-buffered solution.

To prepare a variety of buffer solutions.

To find out the effects of concentration on the pH.

During the lab session for the experiment, the following materials and apparatus were required.

• Solid buffers –Tri-Sodium Citrate (TSC) and Tri-HCL
• NaOH, 0.5M
• HCL, 0.5M
• PH meters
• Beakers

The following procedures were followed during the lab session to ensure that the experiment was performed successfully.

Part 1: Preparation of the buffer solutions.

You will be making up a TSC buffer solution to pH 6.0 and a Tris-HCl buffer to pH 8.0.

The weight of the solid buffer that needed to prepare 100ml of 0.1M solution. Then the solid buffer was weighed and dissolved in 50ml of water.

By using the pH meter the pH of the solution was measured and then changed to the desired pH by using the HCL (0.5) or NaOH (0.5) a drop at the time, then the beaker was swirled after the application of each drop.

More water was added until the 99mL of the solution was achieved and the pH was checked once again. In the case where it had changed more NaOH or HCL as added to rectify it, it was recommended to use a lower concentration of the acid or the base

The volume of the solution was made to 10mL

Part 2: Determining the effects of concentration on the Ph.

10Ml of each of the buffer solution which was prepared in part was diluted by adding 90mL of water to achieve a concentration of 0.01M.

Definition of Buffer?

10Ml of the diluted buffers was diluted further to achieve a concentration of 0.001m.

The pH of both the undiluted and the diluted buffers solution was measured

Preparation of standard solution

A weighed amount of substance was placed in a volumetric flask.

A small amount of water was added to the volumetric flask.

The solid is dissolved in water by gently swirling the volumetric flask.

More water is added to the solution until it reaches the etched mark on the neck of the volumetric flask.

The solution was then mixed thoroughly by inverting the flask several times to enable the solution to mix appropriately

The results which were obtained during the experiment were recorded and tabulated as shown below.

Part 2

Tris-HCL

Tris-HCL

Part 1; for the preparation of the buffers

Number of moles =mass in g/molar mass

  n =m/M

x = 0.1 *0.1

=0.01

n =mol/dm2

Tris HCl

0.01*157.6

= 1.576g

TSC

0.01*294.1

= 2.941g

The data which was collected was very sufficient to achieve the goals of the experiment. The experimental data which was collected confirms what was theoretically predicated; that the pH value of the buffer solution was to be lowered when the concentration was reduced (Stenesh, 2013, p. 147).

From the results which were obtained it was found out that the amount of Tris-HCL that was required for the preparation of 100mL of O.1M of pH 8 was 1.576g while that was need for the preparation of the 100mL TSC with 0.1M.

The pH for both the Tris-HCl and the TSC reduced when the concentration of the buffer solution was reduced. The pH value for the Tris-HCl solution when the concentration was o.1M the pH was 7.96, and when the solution was diluted further by add 90Ml of water to attain the concentration of 0.001M the pH was lowered to 7.92.

For the case of TSC when the concentration was 0.01M the pH value was 6.49 and when the solution was diluted further, and the concentration of 0.001M was attained the pH value of the buffer reduced to 6.44.

Conclusion

In conclusion, Buffers solutions are the aqueous solutions which consist a mixture of conjugated base and a weak base. The pH of the buffer solution changes slightly when a small amount of strong base or acid is added to it, and they are used to control the pH of an experiment

The central focus for carrying out this experiment was to find out how the buffer solution reacts to the dilution in comparison to a non-buffered solution. To produce some standard buffers while ensuring that all the components are measured out accurately

Sufficient data was obtained during the lab session which was further analyzed. It was found out from the results of the experiment that the pH of the buffer solution was lowered when the concentration was reduced. The pH value for the Tris-HCl solution when the concentration was o.1M the pH was 7.96, and when the solution was diluted further by add 90Ml of water to attain the concentration of 0.001M the pH was lowered to 7.92.

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