Paper Chromatography Lab Report

Additionally, Rf values are also dependent on the polarity of molecules. The more polar the molecule is, the smaller Rf value, and the less polar the molecule is, the lager the Rf value. Therefore, the outcome

Chemistry 102 is the study of kinetics – equilibrium constant. When it comes to the study of acid-base, equilibrium constant plays an important role that tells how much of the H+ ion will be released into the solution. In this lab, the method of titrimetry was performed to determine the equivalent mass and dissociation constant of an unknown weak monoprotic acid. For a monoprotic acid, it is known that pH = pKa + log (Base/Acid). When a solution has the same amount of conjugate base and bronsted lowry acid, log (Base/Acid) = 0 and pH = pKa. By recording the pH value throughout the titration process and determining the pH at half- equivalence point, the value of Ka can be easily calculated. In this experiment, the standardized NaOH solution has a concentration of 0.09834 M. The satisfactory sample size of known B was 0.2117 g. The average equivalent mass of the unknown sample was found to be 85.01 g, pKa was found to be 4.69, which was also its pH at half-equivalence point and Ka was found to be 2.0439×〖10〗^(-5). The error was 1.255% for equivalent mass and 0.11% for Ka. In other word, the experiment was very precise and accurate; the identity of the unknown sample was determined to be trans-crotonic by the method of titrimetry.

Therefore, the initial moles of acid and base were expected to be of lower value than those referenced. The dV uncertainty shown in the sample calculations page +/- 0.44 mL displayed this source of error between the calculations of moles of acid, the half equivalence point and the pKa; accounting partially for the percent error in the molar mass and pKa of the unknown acid versus Maleic (C4H4O4). Both Figures 3 and 4 were used to identify unknown acid *B4QK as 3,5 Dimethoxybenzoic (C9H10O4). The titration curve only had one inflection point, thus one equivalence point as demonstrated in Figure 3; showing that the acid was monoprotic. The

If the levels were not proportional, they would be less likely to share this relationship. d. Ys it is reasonable to conclude that the leucine acid is binding to the RNA. This is because of the proportional relationship of the graph. As one amount increase, so does the other.

A compound’s structure will affect its polarity, along with affecting the Rf values due to the polarity of the compound. The least polar the compound the farthest it’ll move on the TLC plate, the more polar the compound the less it’ll move on the TLC plate. The two compounds that I used in lab consisted of Caffeine and Ibuprofen. Caffeine is a very polar molecule, due to the carbonyl groups that are present within the compound, these two functional groups of carbonyl on the Caffeine structure greatly add to the polarity of the compound, along with the lone pairs of the nitrogen that are present also affect the polarity of the compound. Ibuprofen is significantly less polar than caffeine, but had a much greater Rf value than caffeine due to the polarity (since it is less polar than

Comparing Rf values, S2, Ibuprofen, has a similar Rf value to Aleve, but because it separated into two components, one having a higher Rf value than Aleve, it is not likely that the main ingredient in Aleve is ibuprofen. Standard S5, naproxen sodium, has a smaller Rf value than Aleve, but it is the next closest one. Comparing both S2 and S5, I believe S5, naproxen sodium, is present in my sample. S6, aspirin, has an Rf value that is too small to be the major ingredient in

The he investigated an organic compound of dinitrochlorobenzene, this encouragingly stained the amino acids bright yellow and making them stand out in a clear band when subjected to partition

Colorimetric assay is a process of determining a concentration of a solution based on absorbance of light. The purpose of this lab is to determine if the Bradford assay is an accurate way to determine an unknown concentration of two samples of protein. The Bradford assay is done by measuring wavelength of light passing through a cuvette filled with Bradford dye and concentrations of PBS and proteins. After the cuvettes are mixed they are placed into a spectrophotometer to measure wavelength. The wavelength given will be used to plot a standard curve based on concentration (x-axis) and wavelength (y-axis). The standard curve is then used to measure an educated guess on the concentrations of unknown protein concentrations. We hypothesized that if we use the Bradford assay and colorimetric spectrophotometry we can determine an accurate concentration of two unknown concentrations of proteins. The results of this lab failed to reject our hypothesis based on accurate measurements of protein concentrations. The standard curves are drawn with a linear increasing slope. The Bradford assay is an accurate way to demine the concentration of an unknown concentration.

Aspartate and Glutamate are the two negatively charged canonical amino acids, due to their negatively charged side chain groups, and therefore these amino acids would contribute to greater negativity within the H subunit. The spacing of bands visible on the polyacrymide gel of the gel electrophoresis is regular because the negativity of each isoform is determined by the subunits which comprise it (either the H or M subunit). Therefore the negative charge on each isoform will change at regular intervals as the subunit composition of the isoform

The titration curve of the unknown exhibited many characteristics, such as equivalence points, pKa of ionizable groups, isoelectric point, and buffer regions, that are particularly distinct to lysine. For unclear reasons, the pH during the titration did not reach the pH for pure 0.2 M NaOH nor 0.2 M HCl and normal equivalence points expected at two extreme ends of the titration curves for all amino acids were not observed. The titration of a phosphate buffer showed that the buffer capacity is directly proportional to the molarity of the buffer. However, our results showed that although the initial pH of the phosphate buffer was less than the pKa value, the measured buffer capacity was higher towards acid than base. The accuracy of the pH meter and calibration process was questioned under assumptions that the pH of the prepared phosphate buffer was actually above pKa.

Our lab group’s goal for the experiment was identifying two mystery compounds, labeled “X” and “Y”. Through multiple trials, we first built Compound Y by using hydrochloric acid on compound X. We put Compound X under a small flame using a bunsen burner to test the existence of chlorine. After we created Compound Y, our group then found the melting point on both compounds and examined the pH properties and solubility of them. This is how we discovered the empirical formula of X and Y. We titrated the two compounds and determined their gram equivalent weights, found the molar weight by cooling the compounds at freezing point, and finally examined the mass and Infrared spectra to analyze the structure. During our experiment, we discovered both

[A-] / [HA] 10^(1) = 10^(log [A-] / [HA]) 1 = [A-] / [HA] Ratio is 1:1, thus 50% of histidines in a protein will likely be protonated in an environment of pH = 7. At pH = 7.4 7.4 = 6 + log [A-] / [HA] 1.4 = log [A-] / [HA] 10^(1.4)

Name ____________________________ I) Introduction All cells contain four major types of macromolecules: carbohydrates, lipids, nucleic acids, and proteins. In today’s lab, we will be studying three of the four-proteins, carbohydrates and lipids. Various chemical tests can be used to detect the presence of each of these molecules. Most of the tests involve a color change visible to the eye. If a color change is observed, the test is considered positive. If the color change is not observed, the test is negative, indicating that a particular molecule is not present. In all the chemical tests we will be performing, we will also be using a control. In most cases, the control will be a sample of

In doing the lab, one was able to determine the characteristics of the given solutions, containing different macromolecules, whilst doing the multiple tests. The tests performed were,

The topics of these experiments are both important processes known as identification and quantification. They were also used to review and introduce new lab methods such as titration and the Bradford assay. The identification was used to determine the identity of unknown amino acid #11 and the quantification was used to determine the concentration of unknown protein #11. The identity of amino acid #11 was found to be lysine, and the concentration of protein #11 was calculated to be 0.51 ± 0.019 ug/uL with a 3.67% error, reflecting accuracy in the results.