Beakers and measuring Essay Example for Free

Beakers and measuring Essay Chemical engineers exploit chemical reactions to produce materials on a commercial scale. One of their principal activities is the design and operation of chemical reactors. In order to accomplish design goals, the engineer often needs to know the kinetics of a reaction the factors that influence the rate of the reaction. In what follows, a brief discussion of the basic ideas in chemical kinetics is presented along with the mathematical models used to study the kinetics of chemical reactions. The close resemblance of the mathematical equations modeling chemical kinetics to those modeling population dynamics will become apparent. Appropriate links to topics in population dynamics will be indicated for you to explore if you so desire. Reaction Rates A chemical reaction involves one or more substances (reactants) that react to produce other substances (products). As the reaction proceeds, some chemical species are depleted while others are formed. Certain laws govern this process, and these laws can be expressed in terms of mathematical equations Balance Laws One of the assumptions made in chemical kinetics is that the number of atoms is preserved, i. e. atoms are neither created nor destroyed. For example, if there are atoms of Oxygen, , present before the reaction begins, then there will be the same number, , of atoms of Oxygen during all stages of the reaction. This is illustrated by the following stoichiometric equation describing the decomposition of nitrous oxide (a gas) into nitrogen and oxygen gases (do not confuse the nitrogen and oxygen gases, and , with the elements Oxygen, , and Nitrogen, ): PLAN: I must produce a piece of coursework investigating varrying rates of reaction, and the effect different changes have on them. The rate of reaction is the rate of loss of a reactant or the rate of formation of a product during a chemical reaction. It is measured by using the following caculation: Rate of reaction = 1 divided by Time taken for rection to conclude. According to the collision theory of reacting particles, there are five factors that can affect the rate of a reaction: temperature, concentration (of solution), pressure (in gases), surface area (of solid reactants), and catalysts. I have chosen to investigate the effect temperature has on a reaction. This is because temperature is practical and easy to investigate practical. Time is a serious element in my investigation, the preparation of a solid in powdered and unpowdered form would take longer to prepare, and it is difficult to get accurate readings due to the inevitabilities of human errors. A 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 cause a series of anomalous results. AIM: To observe the effects of a change in temperature on the rate of a reaction between Sodium Thiosulphate and Hydrochloric acid. The reaction that will be used is: Sodium Thiosulphate + Hydrochloric Acid Sodium chloride + water + Sulphur Dioxide. (In symbol form) A series of experiments will be carried out changing the temperature while other factors remain constant. Both the sodium thiosulphate and the Hydrochloric acid are soluble in water. My first recording will be demonstrated at room temperature, this will be discovered by using a thermometre, I shall wait until the temperature remains constant before proceeding. When varrying the temperature I shall use a water bath to heat up the solution allowing it to reach the necessary temperature. A preliminary investigation was used to decide which apparatus was appropriate and the varriation of the temperatures. The results of my preliminary investigation are below: My preliminary investigation allowed me to discover that any temperature below 20 C reacted too slowly, and 90i C reacted too quickly to be worth including in my final investigation. I have decided to operate the final investigation using the following apparatus: 1 thermometer = to allow me to test the temperature of the solution. 2 measuring cylinders = to measure the amounts of sodium thiosulphate and Hydrochloric acid used. 1 heatproof mat = for the experiment to place safely on. 1 stopwatch = to allow me to time the rate of reaction.   5 waterbaths = to be set at varried temperatures (ranging from 40-80 C) to heat the solution. X board = to place the conical flask (containing Sodium thiosulphate/Hydrochloric acid solution) on allowing me to observe the rate of reaction. 1 Conical Flask = to contain the solution . 1 pair of tongs = to allow me to pick up the beaker safely after it has been heated. 1 pair of goggles = to protect my eyes from any rogue substances they may be subject to. During this investigation I have decided to use Sodium Thiosulphate in the concentration of 0. 03 moles per litre, 50cm shall be used in each experiment. I will be using Hydrochloric acid in batches of 5cm for each experiment. METHOD: collect nescessary apparatus and assemble in an appropriate fashion.   Using a measuring cylinder, collect 50cm of Sodium Thiosulphate and place into the conical flask. Heat to appropriate temperate using the waterbath, check the accuracy of the water baths temperature by using a thermometre. Place the X board under the flask.   Add 5cm of dilute hydrochloric acid swirling the flask to mix the two solutions. Using a stopwatch, start timing straight away.   Keep eyes on the cross and stop the clock when the solution has gone cloudy and the cross is no longer visible.   Repeat experiment varrying the temperature.   Averages will be taken to improve the credibility of the findings, and present solid grounding for the final conclusion. The repeat results will help to iron out any anomalies and the average will give a good summary of the results of the experiment. However if one set of results is entirely different to the other, a third experiment will be performed to replace the anomalous set of results. Safety A pair of goggles will be worn during the heating part of the experiment in order to protect the eyes. An apron will also be worn to protect the skin and clothing. When handling hot beakers and measuring cylinders a pair of tongs will be used.