Crystal Violet Lab

The absorbance is proportional to the concentration of the chlorine dioxide in water. Indicators used for this technique include N,N-diethyl-p-phenylenediamine, chlorophenol red, and methylene blue (APHA 1998; Fletcher and Hemming 1985; Quentel et al. 1994; Sweetin et al. 1996). For example, chlorophenol red selectively reacts with chlorine dioxide at pH 7 with a detection limit of 0.12 mg/L. The interferences from chlorine may be reduced by the addition of oxalic acid, sodium cyclamate, or thioacetamide (Sweetin et al. 1996). APHA Method 4500-CLO2-B, iodometric titration analysis, measures the concentration of chlorine dioxide in water by titration with iodide, which is reduced to form iodine. Iodine is then measured colorimetrically when a blue color forms from the production of a starch-iodine complex. The detection limit for this method is 20 µg/L (APHA 1998).

Purpose: The purpose of this experiment is to use kinetics to study a solvolyis reaction

The rate law of a reaction relates the concentration of the molecules involved in the reaction to time, allowing us to determine how fast the reaction proceeds and what the reaction mechanism is. Based on the data given on the reaction rate of A and B, we can find the order of the reactants and the average rate constant for the experimental rate law.

Also it is important to consider the spectrometers used in this lab, which had capped out above an initial absorbance of 2 and higher in the lab, which skewed all future readings since it was impossible to record from that value, which led to inaccurate readouts for the absorbance values. A major source of error was that a different volumetric pipette was used to measure the initial absorbance and in Trial 1a than the micropipette used in the other four trials. Though both volumetric pipettes were 1 mL, the possible miniscule differences between the two glassware could have created a significant difference in the tiny volumes. The experiment could have been improved by use of a UV/Vis rather than a Spec, which could improve the precision and accuracy of the measured absorbances and thus decrease the uncertainty. Additionally, measuring the absorbances for a longer duration of time so that a significant deviation from linearity could be observed could decrease the uncertainty in the reaction order with respect to Bromophenol blue. The best alternative could involve measuring manipulated concentrations directly against time instead of absorbance since the values would be in our control instead of in the machine’s control, which tended to show inevitable

The Light, Color and Solutions lab focuses on how light is absorbed distinctively by different solutions. In addition, the lab teaches how to use and read a spectrophotometer. The lab also demonstrates Beer’s Law by changing the cell’s path length and ultimately the solution’s ability to absorb light. All of these aspects are the main purpose of this discovery lab.

In conclusion, using spectrometer to determine the absorbance spectrum of each test tube filled with different mL of Cobalt Chloride Hexahydrate. Using a weighing boat, 5.9485g of Cobalt Chloride Hexahydrate was dissolved in a 100mL of deionized water. When the first 0.25Ml was measured out with a graduated cylinder, to get 0.20ml, 0.15ml and 0.1ml. Dilution was repeated to fill up the solution in the volumetric flask up to 100

The initial rate law is used instead. Initial Rate Law utilizes varying the concentration of the bleach and measuring the differing initial rates of reaction and using the rate relationship shown in Equation 5. The variable x represents the reaction order. This concludes that the reaction order of the Commercial Bleach used in this reaction is first-order because the value of x found was 0.913. The percent error of this first order reaction value is 9.53%. This percent error can be accounted for The fact that both the Blue #1 dye and the bleach are first order reactions on their own, it can be concluded that the overall reaction of the Blue #1 food dye and bleach is second order because the exponents of each individual reaction can be added together to get the overall reaction order of the

During the lab, while the concentration of one reactant varied, the concentration of the other reactant was held constant. The experiment was completed in this particular manner because the concentration of one reactant had to remain the same in order to discover how varying the concentration of the other reactant affected the reaction rate. Learning how to control the rate of a chemical reaction is a big advantage. For example, knowing that the rusting of iron can be slowed by painting the metal or covering it with certain substances is beneficial. The purpose of this experiment was to determine the rate law of a chemical reaction by calculating the change in the rate of the reaction as the concentration of the reactants are varied.

In the first part of the experiment, best absorbance range was measured to be from 0.1228 to 1.8053 where error value was near zero. Methylene blue solution with an absorbance 1.8053 may indicate problems with the accuracy of the detector (e.g., a photomultiplier) .Since the detector system examines the transmitted light of the cuvette, the absorbance is calculated from this value. When transferring the linear transmission unit to the logarithmic absorbance unit, the accuracy is exponentially reduced with rising values. Based on the result obtained from part I, analytes in part II were diluted in 1:20 or 1:10 to generate absorbances that were within this range. Compared to theoretical Ctotal calculated from solution preparation in the second

The amount measured are merely estimates, as there are always uncertainty of 0.2 mL, which is a significant amount when dealing with small amounts of solution. Next, the rate constant at 40°C would be 5.0152 s-1 by using the equation found in the graph of ln absorbance versus time: y=3.2527(1/40) + 4.933 = 5.0152 s-1. Nevertheless, to the study the rate of the chemical reaction and how it is affected by concentration of the reactants, the rate constant, and activation energy is important. According to the chemist, Kim Davis, increasing the temperature increases the rate of the reaction because by increasing the temperature of a system the average kinetic energy of its constituent particles are increasing. As the average kinetic energy increases, the particles move faster, collide more frequently, possessing greater energy when they collide, therefore increasing the rate of the reaction. Moreover, concentration increases the rate of the reaction because the more reactant particles that collide per unit of time, the more often a reaction can occur. As a result, this experiment fostered knowledge on the relationships between the variables of the rate

where the rate reaction is represented as a function of the concentrations in the chemical equation with time.3 The general chemical reaction can be shown as

As the rate of reaction is dependent on the concentrations of the reactants, a rate law for this experiment at 23.5℃ is: Rate = k [KIO3]^n[NaHSO3]^m. The instantaneous rate is the change in product formation at a moment in time. The tangential slope on a curved lined graph will give the instantaneous rate. “The slope value is the instantaneous rate at the time indicated at the point which the tangential line touches the concentration curve. The best

Here, m and n are called –reaction order, k is called- rate constant which depends on temperature.

Investigations into the mechanics of chemical kinetics can reveal invaluable information relating to the rates of reaction. There are numerable applications of reaction rates, knowledge in this area is pivotal for industrial, commercial and research sectors. Thus, allowing them the ability to manipulate a variety of factors of chemical reactions with the use of reaction rates. In the scope of the kinetics of clock reactions, there is a range of information that can be obtained about reaction rates (Shakhashiri, 1992).

Rate of reaction is a way of determining the speed at which a reaction proceeds. It can be calculated by measuring the appearance of a product or the disappearance of a reactant over time. Reactions occur when the particles of the reactants collide successfully. The more successful collisions between particles, the faster the reaction rate. There are factors that affect collision theory and consequently the rate of reaction. High concentration of reactants results in more particles and a higher likelihood of successful collisions. Higher temperature of the reaction also increases the rate of reaction because the energy of the particles is higher which again increases the chances of successful collisions. (Lawrie RYAN, 2000). On completion of this experiment, the reaction orders can be