Lab Report : Proper Laboratory Technique

The protein molecules in many foods provide the amino acid building blocks required by our own cells to produce new proteins. To determine whether a sample contains protein, a reagent called Biuret solution is used. Biuret solution contains copper ions. However, the chemical state of the copper ions in Biuret solution causes them to form a chemical complex with the peptide bonds between amino acids (when present), changing the color of the solution. Biuret solution is normally blue, but changes to pink when short peptides are present and to violet when long polypeptides are present.

1. Benedict’s solution is added to white grape juice and heated. The color changes from blue to orange. Based on this result, what biological molecules are

There were many ranges of color changes in the Benedicts test and Iodine stain. For the Benedicts test, this oxidation/reduction response changes the arrangement of the reducing sugar creating a colored precipitate. The change in color is correlated to the first concentration of the reducing sugar. For the iodine test, the three dimensional structure of various polysaccharides permits them to react with the iodine stain to produce a certain color. As far as the molecular level, there is an OIL – RIG method. Oxidation occurs when a substance gains oxygen or loses electrons or hydrogen (OIL – oxidation is loss) and reduction occurs when a substance loses oxygen or gains electrons or hydrogen (RIG

The primary goal of this laboratory is to correctly identify an unknown substance. To achieve this task, one may use various tests that reveal both chemical and physical properties of a substance. By comparing the results of a known substance and the unknown substance, one may eliminate alternative possibilities and more accurately predict the undisclosed compound. Furthermore, by performing these tests, data can be collected and verified regarding chemical and physical properties of the unknown. Understanding the chemical properties of a known substance aids one’s understanding of the unknown based on comparative analysis of the results of the tests.

The mole is a convenient unit for analyzing chemical reactions. Avogadro’s number is equal to the mole. The mass of a mole of any compound or element is the mass in grams that corresponds to the molecular formula, also known as the atomic mass. In this experiment, you will observe the reaction of iron nails with a solution of copper (II) chloride and determine the number of moles involved in the reaction. You will determine the number of moles of copper produced in the reaction of iron and copper (II) chloride, determine the number of moles of iron used up in the reaction of iron and copper (II) chloride, determine the ratio of moles of iron to moles of copper, and determine the number of atoms and formula units involved in

A cell, the building block of all living organisms, is composed of four fundamental biomolecules: proteins, carbohydrates, sugars and lipids. Proteins provide a vast amount of functions cells such as they serve as enzymes, provide structural support to cells, and act as antibodies. Reagents are used to spark a chemical reaction. The reagent used to detect protein traces in a substance is Biuret’s. Biuret’s will turn purple if proteins are present and blue if they are none. Biuret’s copper particles, have a charge of +2, are diminished to a charge of +1 when peptide bonds, which are in proteins, are present, creating the color change. Polysaccharides, which are carbohydrates, are most notably known to provide energy to the body, but they also help in breaking down fatty acids. Iodine is the reagent used to determine whether a substance has starch in it. The iodine/starch complex has energy levels that are only for retaining unmistakable light, giving the complex its extraordinarily dark black-blue shade. If there is no starch found, iodine will remain its natural yellowish-brownish color, but if starch is present, iodine will turn blue-black. Monosaccharides, which are sugars, like polysaccharides, provide the body with energy. To detect monosaccharides, the reagent, Benedict’s, is used. Benedict’s reagent is added to a test tube, then it is placed in

2. When 2.00 g of NaOH were dissolved in 49.0 g water in a calorimeter at 24.0 ˚C, the temperature of the

Introduction: In this lab, we studied biomolecules. Biomolecules are molecules that are existent in all living organisms. The four biomolecules, we are learning in class are proteins, carbohydrates, lipids, and nucleic acid. The three biomolecules being addressed in the lab are proteins, carbohydrates, and lipids.

The Iodine Test is used to identify the presence of starch or glycogen. If starch is present, the Lugol’s iodine solution will react with the solution being tested to form a dark blue or violet colour. If glycogen is present, the solution will turn a reddish-brown or brown-blue colour (Harisha, 2005, p.44). Using this test, it is possible to determine

If this substance further reacts to the bacteria then a red color will form at the top which will make the test positive if it stays a copper color then the test is negative. This test takes the longest because the process it has to go through. This test is recorded every ten minutes to see if there was any change up to an hour. The next test that was perform was the Phenol Red broth test for both carbohydrates glucose and lactose. Each of the test has a red pH indicator to determine if the fermentation end products and its ability to enzymatically convert the

Our data collection had many different results. First the starting color of the solution in the beaker was yellow (the solution had not yet changed colors). Fifteen minutes after the starch was in the beaker the iodine turned like a olive color. The starting color in the bag before fifteen minutes was clear (no color change was present). Fifteen minutes after the starch was in the iodine the bag had turned blue.

When the enzyme activity is maximized, starch will break down into more monosaccharide than other solution, and when it meets Benedict’s Reagent, monosaccharide will react with Benedict’s reagent and change color into orange. Since most of Benedict’s reagent reacted, the supernatant in the centrifuge tube after centrifuged will have less blue color and more clear. If the solution is measured in the spectro-vis spectrometer with 635nm, which is orange color, less light will be absorbed into the solution and the record will show the lowest

In this experiment a solution of Vitamin C is added to a solution containing of known excess of iodine. At this point, the solution will turn blue-black in colour and this excess amount of iodine can then be titrated against standardized sodium thiosulphate. (^citation here) This technique is called back-titration.

| The reaction between glucose and Benedict’s solution produces a precipitate. This precipitate can be swirling around or sinking to the bottom possibly creating an unfair test between each concentration.

Biuret reagent tested for the presence of protein, which remains light blue with no reaction and changes to purple as a positive control;