Ph and Buffers Lab

In this lab, the purpose was to determine the stability of a substance after adding an acid or a base. The results claim that liver and buffer are the most resistance to change in pH. Looking at figure 3, buffer and liver both maintain a stable pH even with the addition of an acid or base. However, potato and water have less buffer in them since their pHs did change. In figure 3, the potato acid’s pH level decreased by two, and the potato base’s pH level increased by two. The level of pH of a water acid decreased by 4, while the water base’s pH increased by 5. These results all tie to the fact that buffer is a substance that maintains a stable pH; the presence of buffer in organisms help maintain homeostasis by binding or releasing hydrogen

The materials used in this lab were, two glass beakers, four dialysis membranes: 20 (MWCO), 50 (MWCO), 100 (MWCO), and 200 (MWCO), a membrane holder, a membrane barrier, four solutes: NaCl, Urea, Albumin, and Glucose, a solution dispenser, deionized water, a timer, and a beaker flush. The four dialysis membranes are placed between the beakers and during each trial, certain concentrations are increased by adding one of the four solutes in the left beaker. Deionized water is added to the right beaker and replaced before the next test. A timer is adjusted to 60 minutes and the barrier between the beaker descends, allowing the solutions in each beaker to have access to the dialysis membrane separating them. The concentration is checked at the end of the 60-minute period indicating diffusing from the left to right or vice versa. If diffusion occurs in the experiment, repeat with the same membrane and change the concentrations. If no diffusion occurred, continue to the next sized membrane.

After weighing dialysis tubing of starch/sodium sulfate and adding the solution to two test tubes, the tubing was placed in a beaker containing a solution of albumin and glucose. Next, 1.0 mL of albumin and glucose were then placed in two test tubes labeled solution start. The tubing in the albumin/glucose solution was kept inside the solution for 75 minutes. Every 15 minutes the solution and tube was mixed (Keith et al., 2010).

Table 1 shows the contents of the bags and the content of the concentration it was submersed in. Bags 2-4 each contain a solution of both sucrose and water. These bags were each put into beakers containing hypertonic solution. These bags gained weight over time because the water moved from its high concentration inside the beaker to the low concentration inside the membrane of the artificial cell, the membrane being the bags that consisted of dialysis tubing. The

A buffer is a solution that resists changes in pH when H+, OH-, or H20 is added. By using standard lab equipment, a lab pro diagnostic tool, and acidic and basic solutions, the pH can be found. By recording the pH while adding a base or an acid gradually to a buffer solution you can find the capacity of each buffer to resist drastic changes in pH. The best buffers will keep a solution from becoming either too acidic or basic with the addition of a strong base or acid.

To start out this study the difference between acids and bases has to be identified. Acids have very low pHs and have a high concentration of hydronium ions, while bases have a high pH and have a high concentration of hydroxide ions. The difference between strong bases and acids, and weak bases and acids is the amount of dissociation. Strong bases and acids dissociate a large amount and let go of their ions in solution, while weak bases and acids may only let go of some of their ions. This is important because if the unknown solutions aren’t strong acids or bases then using their ions to calculate the pH of the solutions will give false results (Diffen 2012).

When using different methods to measure pH levels there are some tools that can be useful. Some more than others but by putting into action the different methods it may determine which tools will work best and give the best results when testing the pH within a solution. The pH, which stands for the proportion of hydrogen ions in a solution, could be acidic (acidosis), neutral or basic (alkaline). The pH scale goes from numbers 1 through 14. A pH of 7 is neutral;

To prevent fluctuation in the pH, a solution known as a “buffer solution” was used in the experiment. Buffer solutions are mixtures of at least two chemicals which counteract the effect of acids and alkalis. Therefore, when a small quantity of alkali or acid solution is added the pH of the enzyme doesn’t change.

The buffer is a solution that minimises the changes in pH when small amounts of acid or base is added.There are two types of buffer solutions.They can either be acidic or alkaline.An acidic buffer is made by mixing equal amounts of a weak acid and its conjugate base.Similarly, an alkaline buffer has equal amounts of weak base and its conjugate

There were several steps completed to prepare for the experiment. Three dialysis tubes were filled with approximately the same volume of distilled water and then were tied shut. The initial mass (in grams) of the tubes was taken using a triple beam scale. I then filled three 500 mL beakers with 400 mL of water each and dissolved different masses of solute (table sugar) in each beaker in order to make 5%, 10%, and 20% solutions. The beakers were labeled accordingly, and then 20 g, 40 g, and 80 g (respectively) of table sugar was weighed out using a digital scale and placed into the corresponding beakers. The sugar was stirred in using a stirring rod until all of the solute was completely dissolved.

We will observe the reaction of a buffer solution with added acids or bases. We will then evaluate buffering capacity in response to additions added from dilute acid and bases to the buffer.

In which two of the dialysis bag contain tap water. The three other Bags were 20% sucrose 40% sucrose and 60% sucrose. To perform this lab we prepare each of 5 bags with their designated sucrose solution. In this experiment the dialysis tubing acted as selectively permeable membrane. The dialysis bag allows the passage of water molecule only because the sucrose molecule are too large to pass through the membranes. After filling those bags ,we then placed the bags into five separate beakers. Four of this beakers contained only tap waters, and the fifth beakers contains solution of 60% sucrose. We filled the first dialysis bag with 10 ml of tap water, next we filled the second bag with 10ml of 20% sucrose, the third bag was filled with 10 ml of 40% sucrose solution while the fourth bag was filled with 10ml of Tap water (H2O). We made sure that when filling this bags that we removed as much air as possible before clamping of the end of each bag. We also made sure that all of the bags rest soft and floppy instead of firm to ensure that experiment will work properly. Next we placed dialysis bag ,one through four in their own separate beakers which was filled with tap water (H2O), and our fifth bag was full of tap water was placed in beaker filled with just enough of the 60% sucrose solution to cover the bag. All of these bags remained in their designated solutions for 45 minutes. However, all of this bags were quickly removed every

To prove that osmosis occurs across a concentration gradient, a dialysis tube that was filled with 15% glucose solution and a 1% starch solution was submerged in a solution of water and iodine potassium- iodide. The hypothesis was that the weight of the tube would increase and that the solution in the beaker would change color due to diffusion across the membrane. The solution that the tube was submerged in was yellow, because of the iodine, and the tube was clear. After being left to sit overnight, the dialysis tube was revisited. The tube had turned a dark color due to the iodine reacting with the glucose. The iodine diffused into the tub by following its concentration gradient. The concentration gradient meaning the molecules diffuse from an area with high concentration to an area with low concentration. The solution that the tube was submerged in was almost completely clear because the iodine was diffusing into the tube, which also occurred due to the iodine following its concentration gradient. To prove that glucose was present in the beaker, a test was executed with a strip of paper that changes colors when it reacts with glucose. The starch, however, never diffused into the beaker because the membrane of the tubing did not allow for molecules that big to pass through it.

To conduct this experiment we used four pieces of dialysis tubing, four pieces of string, one beaker filled with 10% sucrose and another beaker filled

The beaker was then filled partially with distilled water; 1 ml of potassium iodide was then added, and the solution was tested for the presence of glucose. This data was recorded in table 1 on the data sheet along with the starting color of both the potassium iodide solution and the glucose/starch solution. The dialysis tubing was then submersed into the beaker containing the potassium iodide solution, and set aside for 30 minutes to allow maximum diffusion.