Lab 7: Ph, Dissociation, Hydrochloric Acid Solutions

pH was recorded every time 1.00 mL of NaOH was added to beaker. When the amount of NaOH added to the beaker was about 5.00 mL away from the expected end point, NaOH was added very slowly. Approximately 0.20 mL of NaOH was added until the pH made a jump. The pH was recorded until it reached ~12. This was repeated two more times. The pKa of each trial are determined using the graphs made on excel.

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

An acid is a chemical substance that typically has a corrosive or sour-taste and turns litmus paper red. It has a pH of below 7 and can generally dissolve some metals or even neutralize alkalis. A base on the other hand, is the opposite. They have a bitter taste and are very aqueous. Their pH rating is above 7 and they turn litmus paper blue. In science, pH is the negative log of the activity of the hydrogen ion in an aqueous solution. Basically, we find the pH of a substance by using a testing strip or litmus paper to see the amount of H+ atoms in it. Litmus paper, a common indicator, is used to easily test the pH level of a substance. We can see how acidic or basic a substance is by comparing it to others on a pH scale. A pH scale ranges from 0-14, the most acidic being 0 and most basic being 14. Lemon juice, for example, has a pH of 2 meaning its very acidic. However, average dish soap has a pH of 7-8. The only thing left is a pH level of exactly 7. A pH of 7 is perfectly neutral, not acidic or

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).

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.

a. Aqueous Sodium Hydroxide—NaOH (aq) is a very strong base, which will completely disassociate into Na+ and OH- ions, which would make it a very strong electrolyte. Chemical reaction of the disassociation of Sodium Hydroxide: NaOH (aq)Na+ (aq)+ OH-(aq)

ii. The second part of the titration series involves titration of NaOH with Hydrochloric acid (HCL). Again, three reps of titration and a blank titration have to be completed. A volumetric pipet is used to measure 10.00mL of HCL into three labeled conical flasks. Then the flasks are filled with deionized water until about the 50mL mark. A buret is

To improve the results from the experiment buffer solutions that were not whole pHs could have been used e.g. pH 4.5, 5.5 etc. This would have provided more reliable results as a wider range of results would have been produced. Using pHs with decimals would also help to more accurately determine the optimum pH as the optimum may have been above or below the pH stated in the hypothesis; 8. In this experiment however the optimum is taken at 8 because the graph does not rise again.

The problem that needed to be solved for this experiment was, “How are organisms able to survive and function with proficiency despite metabolic activities that have the disastrous ability to alter pH from a neutral to an acidic or basic environment?” This question needed to be answered by testing different biological materials, as well as tap water, in order to find out what allows modern day organisms to survive such hazardous conditions. A hypothesis that was formulated before experimenting was, “If type of substance is Tap Water, then the changes in pH will be more drastic because water, considered neutral on the pH scale, doesn’t contain a component that will prevent such a change, unlike the content of a buffer solution.” The independent variable for this experiment was type of substance, evidently because this was the part of the experiment that was constantly being changed from trial to trial. The dependent variable for this experiment was pH of the substance because the pH constantly changed depending on the type of substance was being experimented with. The control of this experiment was the tap water and buffer solutions, as the results of the data from the biological materials were constantly compared to the data from both of these solutions.

In this assignment you will be asked to rank aqueous solutions of acids, bases, and salts in order of increasing pH. This is most easily done by first identifying the strong acids that have the lowest pH, the strong bases that have the highest pH, and the neutral solutions that have a pH near 7. The weak acids

Component with a positive or negative charge that break apart in water to form a hydrogen ion. (H+)

I predict that out of the 20 solutions that we are going to be testing, about 6 of them will be an acid, 3 will be neutral and 11 will be a base.

The pH of a solution is the measure of the concentration of charged Hydrogen ions in that given solution. A solution with a pH lower than seven is considered to be acidic. A solution with a higher pH is a base. It is very important for organisms to maintain a stable pH. Biological molecules such as proteins function only at a certain pH level and any changes in pH can result in them not functioning properly. To maintain these constant pH levels, buffer solutions are used. A buffer solution can resist change to small additions of acids or base’s. A good buffer will have components that act like a base, and components that act like an acid.

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

3) Give one example of a weak acid and explain why it called a weak acid.