Commercial TiO2 P25 was obtained from Evonik. Ultrapure water (18MΩ.cm-1) was used throughout the whole experiments. 2.2. Synthesis of photocatalysts The TiO2 nanoparticles were prepared by the sol-gel method described below: 3.9 ml of TiCl4 was slowly added into 10 milliliter of absolute ethanol in reaction vesel, this reaction performed under fume hood at 0°C with vigorous stirring due to exothermic reaction,the high volatilityof TiCl4and also therelease of hydrogen chloride. Then, water was added dropwise during the mixing process.
This helps to indicate whether or not the reaction follows Markovnikov’s Rule, which states that the electrophile (E+) will add to the carbon involved in a double bond that produces the most stable carbocation. If the rule is followed, the reaction will proceed according to the mechanism in Figure 1. In the silver nitrate test, the alkyl bromide is added to AgNO3. The rate of precipitation with 2° should be faster than the solution with the 1° alkyl halide. In the sodium iodide test, the alkyl halide is added to sodium iodide in acetone.
THEORY OF THE EXPERIMENT In this experiment change in the volume of reagents by diluting with water is used as change in the concentration and reciprocal of the time taken for the appearance of blue black colour as the reaction rate. Equation of reaction H2O2 (aq) + 2H+ (aq) +2I- (aq) I2 + 2H2O Hypothesis Hypothesis 1: Decrease in concentration of hydrogen peroxide (H2O2) decreases the rate of reaction (that is, increases the time for reaction to come to completion). In the reaction between potassium iodide (KI), hydrogen peroxide, Sodium thiosulfate (Na2S2O4) under acidic condition. Hypothesis 2: Decrease in the concentration of potassium iodide decreases the rate of reaction (that is increases the time for the reaction to come to completion). In the reaction between potassium iodide (KI), hydrogen peroxide, sodium thiosulfate (Na2S2O3) under acidic condition.
3.7 Homogeneous Catalytic reduction of 4-nitrophenol To investigate the redox catalytic activities of the synthesized AuNPs using the olibanum gum, we selected a well-known catalytic reaction the transformation of 4-NP to 4-AP by sodium borohydride (NaBH4) as a model reaction and the reaction was monitored using UV–visible spectroscopy. The absorption peak of 4-NP undergo red shift from 317 nm to 400 nm immediately after addition of NaBH4, corresponding change in the colour of the solution from yellow to intense yellow was observed due to the formation of 4-nitrophenolate ions under alkaline conditions. This peak at 400nm remained unaltered for many days in the absence of AuNPs. This indicates the inability of NaBH4 itself to reduce directly
In this lab, 3-chloro-3,7-dimethyloctane, obtained during a pervious lab, was used to understand the E2 dehydrohalogenation reaction of an alkyl halide. This reaction is possible because 3-chloro-3,7-dimethyloctane contains a carbon-halogen bond, and the chlorine attached to the molecule is a good leaving group. In the dehydrohalogenation of 3-chloro-3,7-dimethyloctane, 1.320g of the starting compound was obtained. This was then added to a mixture of boiling 6mL ethanol and1mL potassium hydroxide. This solution was then heated for 15 minutes until a precipitant formed.
In Equation 1, for example, increasing the amount of hydrogen peroxide will increase the rate at which it reacts with iodide. The concentrations of iodide and acid remain the same, so the rate will depend only on the changes in hydrogen peroxide concentration. (The iodide is recycled between Equations 1 and 2, and the concentration of acid is high enough that the change in its concentration is small. Note the concentrations of the reactants in the Materials and Equipment section). The rate actually depends on the concentration of hydrogen peroxide raised to a power, called the "reaction order."
This shows that the methylene blue was reduced by accepting hydrogen atoms so it functioned as the final electron acceptor. The reason why the tube that contained both citrate+ iodoacetamide changed in color is because that citrate bypasses glycolysis and directly enters the Krebs cycle. 5. Pre-lab and Post-lab questions: a. Pre-lab
The overall goal of this lab was to produce an unknown oxalate compound, find its percent composition, calculate its molecular formula, and determine the limiting reactant in its formation. A reaction between iron III chloride hexahydrate and potassium oxalate monohydrate produced 3.307g of potassium trioxalatoferrate (III) trihydrate with a 62.0 percent yield. A permanganate titration determined the average percent composition of oxalate was 53.3% with a 2.22% standard deviation. The percent composition revealed the compound’s empirical formula to be FeK3(C2O4)3•3H2O. Potassium oxalate proved to be the limiting reactant.
Nonetheless, the light yellow solid was purified by using the recrystallization technique. The formation of o-nitroacetanilide is inevitable and in order to eliminate it, 95% ethanol is used as the solvent of choice. The ortho isomer is soluble in the cold alcohol solution whereas p-nitroacetanilide in insoluble. As a result, the ortho isomer remains in the liquid solution and the final product, the p-nitroacetanilide is isolated with a final vacuum
The aim of the investigation was to determine the effect of pH on the rate at which catalase decomposes hydrogen peroxide and consequently answer the researchable question “How does pH influence cells and consequently an organism”. The hypothesis, “As the pH deviates from 7 the initial rate of oxygen production will decrease” is supported by the results. The trend displayed in Figure 3 is, as the pH deviates from 7 the initial rate of reaction decreases. Figure 3 shows that the rate of reaction (%O2/s) decreases substantially as the pH increases and decreases to 8 and 6 respectively from a pH of 7. This is indicated as the graph shows that the initial reaction rate for pH 7 was 0.143 %O2/s compared to 0.047 and 0.053 for pH 6 and 8 respectively.