CH 204- Intro to Chem Practice Experiment 3-Enthalpy of Chemical Reaction Dana Lucas Robin Brown TA: Chris February 19, 2018 Introduction The purpose of this experiment was to calculate the change in enthalpy of 2 reactions using Hess’ Law by using a coffee calorimeter to measure the temperature changes in the sub reactions for MgO and a neutralization reaction. Germain Hess published this law in 1840, which described the first law of thermodynamics. In Hess’ Law, “the enthalpy change in a chemical reaction is independent of any intermediate reactions; that is, it is the same whether it takes place in one or several stages”1. The change in enthalpy can be described by the equation: The enthalpy, or heat, of reaction is described as products
Two clear solutions are mixed, producing a new clear solution. Then, after a period of several seconds, the solution turns dark blue. As mentioned, chemical kinetics measures how fast a reaction is occurring. To perform the iodine clock reaction in this science fair project, you will mix potassium iodide, hydrochloric acid, starch, thiosulfate and hydrogen peroxide. The time it takes for the reaction mix to turn blue will be measured with a stopwatch.
Then plates will be allowed for incubation at 37°C and by using hemocytometer, after staining with 0.4% Trypan Blue every 24 h, number of cultured cells in the different wells will be counted to calculate the doubling time. d. Cell viability in presence of caspase-3 inhibitor The viability of MCF-7 cells treated with caspase-3 inhibitor and evaluation of drug will be done by using MTT assay. After incubation with caspase-3 inhibitor for 1 h, cells will be treated with different concentrations of drug(s) for upto 48 h after which viability will be
Shayna Salloway AP Chemistry A Snyder 11 September 2014 Title: Finding Mole Ratios of Reactants in a Chemical Reaction Purpose: Experiment using the method of continuous variations to figure out mole ratios of reactants. Procedure: 1. Take the NaClO and the sodium thiosulfate solutions and measure the temperature of each solution. Record in the data table. 2.
Then 5g of Mg was added to the crucible, then the mass, was once again was recorded. 3. Using the Bunsen burner, the crucible was placed over the burner for 1 to 2 minutes then allowed to cool, and then the weight of the crucible was once again measured. 4. Then the table was cleared to prepare for the next lab.
The sensor was kept in oven at 70ºC for few/ 3 hours prior to each experiment session for the purpose of gas molecule desorption. The SWCNT sensor was then placed inside the gas cell in the flow of N2 gas until the equilibrium condition was obtained, i.e. the resistance measurement stabilized. The response of sensor resistance to two different explosive chemical: (i) Dinitrotoluene – DNT, (ii) Ammonium Nitrate, NH4NO3; both oxidizing agent, at different parameters and various concentrations was monitored. Typical baseline resistance for the SWCNT sensor ranged from 10 to 15 Ω.
The reaction mixture is heated at 1010C for 5 hours.19 The figure below shows the corresponding pathway for the synthesis of the dialdehyde. Figure 15 Synthesis of the second part of the macrocycle 3.1.4 Self-assembly of the rotaxane Since the rotaxane has the property of self-assembly, by mixing the three components above in acetonitrile (ACN) for several hours will form the targeted  rotaxane.19 Figure 16 Self-assembly process of the rotaxane Adopted from: Wong, W. et al. Organic & Biomolecular Chemistry 2010, 8 3.2 Detection phase As for Phase II (detection phase), several metal ions will be selected to form complex with the macrocycle and the anthracene fluorescence will be detected. 3.2.1 Preparation of samples For the preparation of samples, two stock solutions, the metal ion and the rotaxane solution will be prepared separately. The solution will be mixed together to form a sample solution, which will be tested for the fluorescence intensity.
Lab Report Experiment 6 Rates of Chemical Reactions By Nikhola Mirashirova Lab Partner: Dina Abetova Section 3, Saturday October 31, 2015 Introduction Rate reaction is the measure of the change in concentration of the reactants or the change in concentration of the products per unit time.1,2 Rate law for this experiment: Rate = k(I-)m(BrO3-)n(H+)p There are several factors which affect the rate of reaction: catalyst, reactant concentration, and temperature.1,2 A catalyst is a substance that changes, increases or decreases, the rate of a chemical reaction but is not being used up during the reaction.3 It provides an alternative way, so that the rate of reaction changes.4 Catalyst, which is used in this experiment, is (NH4)2MoO (0.5 M). In this experiment rate of reaction with different reactants concentration: KI (0.010 M), KBrO3 (0.040 M), and HCl (0.10 M) will be observed. So, this is reaction between iodide and bromate ion under acidic conditions: 6 I- (aq) +BrO3-(aq)+ H+(aq)→ 3I2(aq) + Br-(aq)+ 3H2O The end of the reaction, will be determined by observing color change of solution. Thus, solution should shange color to blue. Blue color appear because of starch indicator.
The formula used to calculate hardness is given below: where D = diameter of the ball = 10 mm d = diameter of impression F = force applied = 10 kN The calculated value was then compared to a journal by Awotunde W.O, Olatunde O.B, Ponle E.A, and Fatukasi S.O from Mechanical Engineering Department of Osun State Polytechnic, Nigeria; published in May 2014, entitled Design, Fabrication and Performance Evaluation of a Hardness Testing Machine. 2.3 Procedure 1. Insert one of the test speciment into the universal testing machine. 2. Rotate the hand wheel clockwise to lower down the test ball.