Chemistry of Life:pH and Buffers Life Sciences Lab Report

Chemistry of Life: pH and Buffers
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Introduction
The different concentrations of ions in a solution significantly affect the behavior chemicals where ions serve in determining the specific properties of a solution (OpenStax College, 2019). In aqueous solutions, the number of hydrogen ions (H+) and hydroxide ions (OH-) determines the pH of a solution as neutral, acidic or basic (Chemistry of life: pH and Buffers, 2016). Additionally, the pH is important in studying biological systems since biological systems requires a specific pH or concentrations of H+ and OH- ions to achieve optimum functionality (Chemistry of life: pH and Buffers, 2016). So, if there is an imbalance in pH levels in the biological systems, physiological processes might not function, therefore these systems use buffers that resists the change in pH when added with acid or bases (Chemistry of life: pH and Buffers, 2016). A buffer contains both the weak acid and its conjugate base or a weak base and its conjugate acid that acts to keep the H+ and OH- to retain the pH even with the additions of acid or base (Chemistry of life: pH and Buffers, 2016; OpenStax College, 2019). In this experiment, the activities performed aims to explain the importance of pH and pH regulation in the different biological systems, to use a chemical indicator to know the pH of a solution, to analyze the buffer capacity of buffer solutions, and to perform the calculations needed to prepare a buffer from a weak acid with its conjugate base (Chemistry of life: pH and Buffers, 2016).
Hypothesis: In the first activity, it is hypothesized that the addition of 0.1 M HCl and 0.1 M NaOH will not change the pH of the buffer while in experiment 2, it is hypothesized that as the concentration of the buffer decreases, the pH measurement also increases with increasing additions of 0.1 M NaOH.
Methodology
Materials
The following reagents were used in the pH and buffers experiment:25ml of pH4 and pH8 sodium phosphate buffer, 50 ml pH 6 sodium phosphate buffer, 30 ml 1M sodium hydroxide, 15 ml 1M hydrochloric acid, and 7ml Bogen's universal indicator. Measuring equipment such as 250 ml beaker, 25 ml graduated cylinder, two 1 ml graduated dropper pipets, and test tubes were used in the experiment. Additionally, Bogen's universal indicator, 3ml graduated dropper pipets, 4 x 5 wells, a test tube rack and grease pencil were also used to complete the activities. Then, the necessary equipment in each activity were labeled.
Procedure
Activity 1: Buffer Effectiveness at Different pH levels
The labeled dropper pipets were placed into their respective buffer solution bottles. Then, about 2 ml of water was added to each well in row a; about 2 ml of pH 4 sodium phosphate buffer was added to each well in row b; about 2 ml of pH 6 sodium phosphate buffers was added to each well in row c; and, about 2 ml of pH 8 sodium phosphate buffer was added in each well in row d. Then, about 2 drops of Bogen's universal indicator was added into each well and the solutions were swirled. The resulting color of the solutions in the first well were matched to the Bogen's universal indicator color chart to determine the pH to be later used as the basis of comparison and were recorded in the data table 1. In the second well, one drop of 0.1 M HCl was added. In the third well, 10 drops of 0.1 M HCl were added. In the fourth well, one drop of 0.1 M NaOH was added. In the fifth well, 10 drops of 0.1 M NaOH were added. All the resulting color in each well were then recorded in data table 1. The activity was documented and the tray used was cleaned for the next activity.
Activity 2: Buffer Concentration and Effectiveness
Dilutions of pH 6 sodium phosphate buffer was prepared. A graduated cylinder was used to measure the volumes of water and the graduations on the corresponding 3-ml pipet to measure the volumes of buffer. Then, about 6 ml of distilled water were added to a test tube with label "50%"; about, 9 ml distilled water were added to test tube labeled "25%;" about, 10.5 ml of distilled water was added to a test tube labeled "12%;" about 6 ml of pH 6 sodium phosphate buffer was added to test tube labeled "50%;" and, about 3 ml of pH 6 sodium phosphate buffer were added to test tube labeled "25%." The different concentrations of buffer solutions were added in each well of the tray where about 2 ml of 100% pH 6 buffer were added in each well in row a; about 2 ml of 50% pH 6 buffer were added in each well in row b; about 2 ml of 25% pH 6 buffer were added in each well in row c; and, about 2 ml of 12.5% pH 6 buffer were added in each well in row d. Additionally, 2 drops of Bogen's universal indicator was added to each well and gently swirled until the color in each well was uniform. The corresponding pH in each row was recorded in data table 2. Then, varying amounts of 0.1 M NaOH were added to each well of the different rows where 1 drop was added in the second well of each row in column 2, 2 drops were added in the third well of each row in column 3, 4 drops were added in the fourth well of each row in column 4, and 8 drops were added in the fifth well of each row in column 5. The solutions were swirled until the corresponding colors were uniform, then were documented and recorded in data table 2.
Results