Nucleic Acid Investigation

1. To prepare a standard solution of oxalic acid and use it to standardize an unknown  sodium hydroxide solution.

Buffers can be used to resist change in pH in an acid or base solution. The purpose of the lab is to understand the properties of buffers in relative concentrations, in the presence of a strong acid/base and dilution of buffer components the ammonia/ammonium buffer system. In this case, these laboratory techniques associated with buffers are performed to determine the pH values in diluted solutions. This is done by observing the Henderson-Hasselbalch equation. This represents the pH value by comparing the p value and the concentrations of a weak acid and conjugate base of a buffer solution, as long as assumptions are valid. From there, a pH vs log can be used from the values obtained. Then, the theoretical pH of solutions can be determined with the addition of a strong acid (HCl) and base (NaOH). From this, the effect of dilution can be viewed when plotting the calculated pH values vs dilution on the same graph.

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).

Three grams of a mixture containing Benzoic Acid and Naphthalene was obtained and placed in 100 ml beaker and added 30 ml of ethyl acetate for dissolving the mixture. A small amount (1-2 drops) of this mixture was separated into a test tube. This test tube was covered and labelled as “M” (mixture). This was set to the side and used the following week for the second part of lab. The content in the beaker was then transferred into separatory funnel. 10 ml of 1 M NaOH added to the content and placed the stopper in the funnel. In the hood separatory funnel was gently shaken for approximately one minute and vent the air out for five seconds. We repeated the same process in the same manner one more time by adding 10ml of 1M NaOH.

1. We measured 2 mL of diluted hydrogen peroxide (the substrate), 1 mL of guaiacol (the product indicator), and 1 mL of neutral buffer (pH 7) with a syringe and disposed it into tubes 1, 2 , 4, 9, 11, and 12.

Each human being has something called DNA. DNA is described as genetics and an extremely long macromolecule that is the main component of chromosomes and is the material that transfers genetic characteristics in all life forms. DNA constructs of two nucleotide strands coiled around each other in a ladder like arrangement with the sidepieces composed of alternating phosphate and deoxyribose units and the rungs composed of the purine and pyrimidine bases adenine, guanine, cytosine, and thymine. Each chromosome consist of one continuous thread-like molecule of DNA coiled tightly around proteins and contains a portion of the 6,400,000,000 basepairs that make up your DNA.

Table 2: Consists of color extract taken from a red cabbage for a natural indicator. The pH reading that was measured by using the pH meter and the result of the pH reading to determine whether the solution was acidic or basic.

When handling the Acid or Base to avoid getting any substance in eyes: Use protective eyewear

By using acid-base titration, we determined the suitability of phenolphthalein and methyl red as acid base indicators. We found that the equivalence point of the titration of hydrochloric acid with sodium hydroxide was not within the ph range of phenolphthalein's color range. The titration of acetic acid with sodium hydroxide resulted in an equivalence point out of the range of methyl red. And the titration of ammonia with hydrochloric acid had an equivalence point that was also out of the range of phenolphthalein.. The methyl red indicator and the phenolphthalein indicator were unsuitable because their pH ranges for their color changes did not cover the equivalence points of the trials in which they were used. However, the

The initial goal of this experiment was to investigate the properties of an unknown acid or base. These properties include pH, concentration, and how the solution behaves once titrated. In order to accomplish these goals, the initial pH of the unknown compound needed to be found through the use of pH strips and/or a PASCO probe. It was also necessary to titrate the unknown compound to find the equivalence point, which would allow the calculation of the initial concentration of the unknown chemicals. In order to see how dilution affected the pH of the unknown compound, it was necessary to dilute the unknown compounds over a series of steps and observe the trend. Finally, it was helpful to test the household chemicals for their acidic or basic properties and compare how they reacted to the reactions of the unknown compounds.

A suitable indicator for determining the endpoint in the neutralization of a weak acid with a strong base is phenolphthalein. Phenolphthalein has a pH range of 8-10. It is colorless in acidic and neutral solutions. According to the titration curve of a weak acid-strong base titration, the pH at the end point is basic. Phenolphthalein only changes color when the solution becomes basic. Hence, it is an ideal indicator for this lab because it will change color when the end point is reached.

First, three titration curves and three second derivative curves were created to determine the average pH at the half-equivalence point from the acetic acid titrations. Titration curves were used as visuals to portray buffer capacity. The graphs and a table, Table 1, that showcased the values collected were created and included below. The flat region, the middle part, of Figures 1, 2 and 3, showed the zone at which the addition of a base or acid did not cause changes in pH. Once surpassed, the pH increased rapidly when a small amount of base, NaOH, was added to the buffer solution. Using the figures below and

The styrofoam cups were used to store the acid (cup was labeled A) and base (cup was labeled B) prepare for them to be mixed. A lid was put on cup A and then the temperature probe was inserted to begin to measure the temperature

In this lab a acid-base indicator phenolphthalein was used to determine endpoint of a reaction HCl(aq) and KOH(aq). At the end point all of the HCl(aq) would have reacted with KOH(aq), and the pH becomes 7. The phenolphthalein would changed colours from colourless to pink indication when enough KOH(aq) was added. The purpose of numerous trials was to use the average volume of the 3 trials with similar measurements.

An acid-base titration is the determination of the concentration of an acid or base by exactly neutralizing the acid/base with an acid or base of known concentration. This allows for quantitative analysis of the concentration of an unknown acid