For this lab the knowledge to tell the difference between a chemical and physical changes was needed. To tell this the knowledge of the five signs of a chemical change was needed. These five signs are color change, odor change, production of bubbles/gas, production of heat/light, and the production of precipitate. Also prior to the lab one question was provided that needed to be answered. This question was what chemical must be present for a color change. The hypothesis that was provided to this question was If Phenol Red is add with the other chemicals then a color change will occur. Methods: To begin the lab 40 mL of Phenol red were obtained in a beaker, and 40 mL of water were obtained in a separate beaker. Next one plastic baggie was …show more content…
of Sodium bicarbonate (NaCHO3), and 5 mL of phenol red solution were all placed at separate location inside the baggie. Finally all the air was pushed out of the bag, the bag was sealed, and the contents were mixed thoroughly. Observation were then recorded and the bag was thrown away. This process was then repeated six more times using different combinations of chemicals. These combinations were: 2 tsp. NaHCO3 and 5 mL phenol red, 2 tsp. CaCl2 and 5 mL phenol red, 2 tsp. CaCl2 and 2 tsp NaHCO3 and 4 mL water, 2 tsp. NaHCO3 and 5 mL water, 2 tsp. CaCl2 and 5 mL water, 2 tsp. CaCl2 and 2 tsp. CaCl2.The question asked at the beginning of the lab was what chemical must be present for a color change to occur. My hypothesis was that if Phenol red was present then a color change would occur. This hypothesis was true because every reaction that had phenol red experienced a dramatic color change while the other reactions did not. In the lab it was also
That mixture was then filtered through a coffee filter. Nine test tubes were prepared in order to perform this dye coupled reaction. One contained 5.0ml of the potato and pH buffer mixture, 2.0 ml of hydrogen peroxide, and 1.0 of guaiacol to serve as a blank for the spectrophotometer. Four test tubes were filled with 2.0 ml of hydrogen peroxide and 1.0 ml of guaiacol, used for measurement by the spectrophotometer, each. The last four were filled with 4.0 ml of the potato and pH buffer mixture and 1.0 ml of peroxidase.
When the students placed the wire containing the sample in the flame it burned a orange/ red color. when this result was compared with the previous flame tests it could have resulted from either CaCl2 or NaCl. Both of these compounds produced an orange flame. After the flame test was conducted, the students performed a litmus test to identify whether the unknown was neutral or a base. When exposed to the red and blue litmus paper, no reaction occurred.
Something that was interesting to find out though, in the description of the reagent color test they show the lighter color on top and the darker one on the bottom. But just as the test that was conducted showed and what Officer had said was that the darker color is always on the top and the lighter on
Summary Determining the concentration of a liquid can be a tricky process involving complex procedures if it were not for science’s ability to test a substance’s absorbency through spectrophotometry. The experiment was carried out to discover the concentration of Red Dye #40 in several common soft drinks. The samples of the dye were diluted, and tested using a spectrophotometer. The absorbencies of these samples were then recorded, and a standard line curve with the concentration equation and R2 value was created with these results. Using the absorbencies of the dye samples, the concentrations of the soda samples were determined using the slope equation provided by the graphing software.
2. Explain what process caused the results. Be certain to back up your response with at least three pieces of evidence. One piece of evidence must be quantitative. Explain how the process worked in this lab
The chemiluminescence part of the experiment, we had to make four solutions labeled as ‘stock solution A, solution A, stock solution B, and solution B’. For the ‘stock solution A’ we put the luminol product, (0.242 g) in a 25 mL Erlenmeyer flask and dissolve it with 2 mL of 3M NaOH. Then we took 1 mL of the ‘stock solution A’ and diluted in 9 mL of water using a 50 mL beaker. Solution A. For the ‘stock solution B’ we mixed 4 mL of potassium ferricyanide solution and 4 mL of hydrogen peroxide solution using a 25 mL Erlenmeyer flask.
These color changes indicate a chemical change, which show that a reaction had occurred. In the first step when o-vanillin and p-toludine, imine was formed. The color change from green to orange suggests that imine appears as orange colored. In the second step, the addition of sodium borohydride reduced the imine into another derivative, which was yellowish lime color. The solution turned clear when acids and anhydrides was added, which indicated the precipitate were dissolved.
I noticed quickly that there was a mystery to how one substance can change into another. I had to find out more. As I sat there waiting, it dawned on me that this change would be gradual. After an hour, there had only been a slight variation in the color, but that change still meant something.
Chemical reactions which cause a change in temperature can be categorized as endothermic or exothermic reactions. In an endothermic reaction, energy will be absorbed by the chemical mixture; in an exothermic reaction, energy will be released. If a beaker is submerged in a mixture with a cooler temperature than the water inside the beaker, heat will be transferred from the water in the beaker to the chemical mixture, making the chemical mixture undergo an endothermic reaction. When the chemical mixture is warmer than the water inside the beaker, heat will be released from the water inside the beaker to the chemical mixture, making the chemical mixture undergo an exothermic reaction. The goal of this lab was to learn about endothermic reactions, exothermic reactions and
This happens when the color batch or recipe for dyes, paints, inks or other pigments is changed during production, leading to a mismatch of colors. Metameric effects are best observed under two or more different light sources and illuminants such as daylight (D65) and incandescent light (illuminant A). Visual test can be conducted using the following steps: Visually compare a pair of metameric sample under one light source within the light booth. Change the light source, for example D65 to illuminant A, and observe the samples for any color mismatch.
Jaspreet Singh Professor Paratore Biology 1 November 1, 2014 Spectrophotometry Identifying Solutes and Determining Their Concentration Statement of the Exercise or of the Problem The purpose of the lab experiment was to attain the following objectives: • Learning to Operate the Spectrophotometer • Construct absorption spectra for cobalt chloride and chlorophyll. Hypothesis If greater and higher concentrations of cobalt chloride are added to each solution then greater amounts of light would be absorbed by each solution. Thus a liner relationship will result in which the absorbance of a substance would be proportional to its concentration, which will be depicted, in a linear graph.
In this experiment, absorbance at A400 was directly proportional to the number of moles of p-nitrophenol. This shows that there is a linear relationship between the absorbance and the number of moles of p-nitrophenol, which later also shows that there is a linear relationship between the absorbance and the concentration of the p-nitrophenol, as the number of moles of p-nitrophenol will increased when the concentration of p-nitrophenol increased. The R2 value obtained for the standard curve is 0.9997, which indicates that the data obtained fit the line of best fit, showing that the data are accurate. The values of absorbance per µmol of p-nitrophenol were then obtained from the gradient of the curve, which will later be used in calculation in determining the enzyme activity. Based on Graph 3, it was shown that the enzyme activity of alkaline phosphatase increased with the increase of MgCl2
PROCEDURE DETERMINATION OF PHOSPHORIC ACID IN THE SOFT DRINKS Black coloured soft drinks such as Coke from Coca Cola and Pepsi contains Phosphoric Acid in them. An experiment will be conducted here to determine the quantity of Phosphoric Acid content in the black coloured soft drinks. In the beginning of the experiment the preparation and standardization of a base solution will be made.
OBJECTIVE The objective of this experiment was to analyze and determine the unknown concentration of a protein solution by utilizing two different colorimetric techniques; Biuret and Lowry. The Biuret method was used with unknown #2 and the Lowery method was used for unknown #1. After the concentration of each unknown was analyzed (by Biuret or Lowry method), the alternate objective was to compare the results achieved by each method and to determine if the results from the approaches were consistent in contrast to each other. THEORY Biuret and Lowry methods use colorimetry as a tool to analyze protein concentration quantitatively.
Properties of Roller Compacted Concrete with Pozzolan as Cement Replacement Material Introduction: Roller compacted concrete (RCC) gets its name from the heavy vibratory steel drum and rubber-tired rollers used to compact it into its final form. RCC has similar strength properties and consists of the same basic ingredients as conventional concrete_ well graded aggregates, cementitious materials, and water_ but different mixture proportions. The largest difference between RCC mixtures and conventional concrete mixtures is that RCC has a higher percentage of fine aggregates, which allows for tight packing and consolidation [1]. RCC may be considered for applications where no-slump concrete can be transported, placed, and compacted