Therefore, it can be concluded that a catalyst has a major effect upon the time taken in a reversible reaction to reach equilibrium in a closed system, but does not have any effect the macroscopic properties of the system. Experiment 9: Equilibrium III – Temperature The purpose of this experiment was to see if changing the temperature has an effect upon the value of the equilibrium constant. This experiment investigated the chemistry of equilibrium using N_2 O_4 ⇋ 〖2NO〗_2. In part one of the experiment, the following conditions were: Volume lock on 1 mole of N_2 O_4 and 0 mole of 〖2NO〗_2 0.0409M of N_2 O_4 and 0M of 〖2NO〗_2 IN 24.47 L at 101.3 kPa No catalyst No unreactive gas Temperature 25°C In part two and three of the experiment, the following conditions were the same as part one, but with: 50°C (part
Based on our data the law of mass conservation was observed through the experiments containing ZnCl2(aq) + Na2S(aq) and Pb(NO3)2(aq) + 2 KI(aq). We gained mass after mixing the chemicals and separating the chemicals for both experiments. In the first experiment the difference in the amount mass from the initial mass was 0.46 g and in the second experiment there was a difference in the amount mass from the initial mass which was 0.75 g. In the demo experiment, the chemical reaction created was the release of nitrogen gas and H2O gas. In the experiment, the chemical reaction created was the formation of a solid ZnS and an aqueous sodium chloride. In the alternative experiment, the chemical reaction created was of
In this experiment various solutions of lead nitrate and potassium iodide were mixed at a number of different dilutions. Through the observation of the amount – or lack of precipitate formed in each dilution, the mathematical relationship between the ions in a saturated dilution may be determined. This relationship is known as the solubility product constant, or Ksp, and is defined as follows, “The Ksp for an ionic solid is given by the product of the concentrations of the ions, each raised to the power of the coefficients in the dissolving reaction. '; (Heath Chemistry). The Ksp expression gives the maximum possible concentration of ions in a saturated solution without causing precipitation.
Since the k values will not change with concentration as long as temperature and the solvent remain constant, k should change as temperature changes1. This is seen in this experiment because the resulting k values of the heated and cooled sections were different from the general reaction. This SN1 reaction is only effected by the change in concentration of the substrate, t-butyl chloride, and not the nucleophile. Some parts of this experiment are extremely vulnerable to error. For example, when initially preparing the initial solutions for the 25 mL and 50 mL Erlenmeyer flasks, it would be very simple to unknowingly add too much of a chemical.
Because a balance, equilibrium constant exists when the ratio of product concentrations to reactant concentrations does not change through further reaction, there is an error in the experiment. The K values are not precise. Only two of them have the same number. The error could be done by a temperature change that is the only form of stress to an equilibrium system that changes the value of the equilibrium constant.
Catalysts. For my preliminary experiments I have chosen to investigate the effect temperature and concentration have on a reaction. I have chosen to investigate these reactants because the are the most practical for the lab and equipment that I have available to use also it would take to much time to prepare a solid in powdered and unpowdered form, and it is difficult to get accurate readings due to the inevitabilities of human errors, and as gas is mostly colourless it is difficult to gauge a reaction changing the pressure, and if a substance is added to give the gas colour, it may influence the outcome of the experiment. Similarly the use of a catalyst complicates things, and if used incorrectly could alter the outcome of the experiment. My preliminary experiments showed me that it would me more practical and time saving if I just altered the temperature of the solution as changing the concentration of the solution was very time consuming.
This was one of my highest yields yet. I felt that this was a good yield because part of this experiment is an equilibrium reaction. Hypochlorite must be used in excess to push the reaction to the right. Also, there were better ways to do this experiment where higher yields could have been produced. For example PCC could have been used.
The heat of formation found for the formation of liquid water was -286kJ/mole. By using Hess’s Law, the heat of reaction for the formation of magnesium oxide was found to be -496kJ/mole which yielded a -17.6% error. A possible source of error could be loss of heat during the reaction that could have affected the final temperature results. Since a real calorimeter wasn’t used and a plastic cup calorimeter was used, there is a good chance that the system lost more heat to the surroundings than it would have if a real calorimeter had been used. That said, using the plastic cup calorimeter is a good substitute for a real calorimeter in classroom laboratory experiment because it still acts as an insulator to keep the heat inside and makes a better calorimeter than other materials because of its high specific heat.
Experiment 1: The Composition of Aqueous Complexes by UV-vis Spectrophotometry CHEM 4310L Analytical Chemistry II Call Section 100 Monday, Wednesday9:40-12:45 Joshua Holley, Kyle McQauid 01/22/14 Introduction The purpose of this experiment is to determine the stoichiometry of a complex ion using Job’s method. In doing so, experience is gained in using the techniques and instrumentation involved in absorbance spectrophotometry. When a metal cation (M) reacts with a ligand (L) a complex forms. The ligand acts as a Lewis base in the reaction and forms a coordinate covalent bond as the ligands lone pair goes to an empty orbital within the metal. To illustrate this: xM + yL → MxLy where x and y are stoichiometric ratios.
So it is not advisable to perform the experiment at high temperatures as the time of reaction is too short, it is not easy for us to record. 4. Why is it not necessary to know how far the reaction has proceeded at the point where the methyl red is decolourized? In the experiment, the number of mole and the molarity of each chemicals used are the same. And the appearance of the pink colour only determines that there are some content of the reaction has processed.