### IODINE CLOCK REACTION COURSEWORK

From the graph the gradient relative rate was measured at 6 points. Error Change in Temperature Problem The room temperature increased as the lab was conducted affecting the lab speeding up the reaction when the temperature increased. Here, the coincidence is not surprising, the chance of a ‘fruitful’ collision is directly dependent on both reactants initially colliding, its often the slowest step even in a multi—step mechanism and if there are no other kinetic complications, the orders of reaction do match the numbers of the balanced equation e. This proved to be a curve – compare the blue rate data curve with the black ‘best straight line’ courtesy of Excel! Reminder [x] means concentration of x, usually mol dm Kinetics of the thermal decomposition of hydrogen iodide. From runs i and ii , keeping [B] constant, by doubling [A], the rate is unchanged, so zero order with respect to reactant A. The graph below show typical changes in concentration or amount of moles remaining of a reactant with time, for zero, 1st and 2nd order. To put this graph in perspective, a 2nd order plot is done below of rate versus [RX] 2. Copying of website material is NOT permitted. A graph is drawn of CH 3 3 CCl concentration versus time. For example, many reactions occur via a single bimolecular collision of only two reactants and no catalyst e. Only then is it possible to derive a rate expression , which summarises what controls the speed of a particular reaction in terms of the relevant concentrations , which is not necessarily all the reactants!

## A-Level Investigation – Rates of Reaction &#150; The Iodine Clock

I’ve made the numbers quite simple to follow the logic of the argument. Some rate data for the inversion of sucrose is given below. Since the gradient rate changes with concentration, it cannot be a zero order reaction. These examples do NOT involve graphs directly, but a ‘graphical’ section of examples has been added in section 5.

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The rate of radioactive decay is an example of 1st order kinetics. We will write a custom essay sample on. Therefore the order with respect to A is 2 or 2nd order. A small and constant amount of sodium thiosulfate and starch solution is added to the reaction mixture. As the iodine molecules are produced they immediately react with the thiosulfate ions and are converted back to iodide ions: Reminder [x] means concentration of x, usually mol dm The courswork graph is a plot of HI decomposition rate versus [HI] squared, and, proved to linear – the blue data line was pretty coincident with a black ‘best straight line’.

Copying of cuorsework material is NOT permitted. There is no possible way to change the speed of reaction as it is a human flaw, therefore using a more precise instrument will be more appropriate for the lab. The hydrolysis of a tertiary chloroalkane produces hydrochloric acid which can be titrated with standardised alkali NaOH aqor the chloride ion produced can be titrated with silver nitrate solution, AgNO 3 aq.

From runs i and iikeeping [B] constant, by doubling [A], the rate is unchanged, so zero order with respect to reactant A. Error Change in Temperature Problem The room temperature increased as the lab was conducted affecting the lab speeding up the reaction when the temperature increased.

# Iodine Clock Reaction: Concentration Effect Essay Example | Graduateway

The stirring motion was not kept constant and affects the time it takes for the potassium iodide to react with sodium thiosulphate as the rate of reaction would increase when the swirling motion is quick. Exam revision summaries and references to science course specifications are unofficial. I’ve also shown how coursedork calculate the rate constant. Let me help you. Starch- Indicator When starch is left in mixture for a long period of time, it starts to degrade and will take longer for the reaction to be seen affect the time taken.

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Example of a rate expression. Measure 5 cm3 of hydrogen peroxide into a syringe. Eric from Graduateway Hi there, would you like to get an essay?

## The Iodine Clock Investigation

This result is backs up the collision theory1 that states in order to show a positive increase in the rate of reaction, the amount of collision must also increase. This frequently causes problems! A plot of HI concentration versus time above was curved showing it could not be a zero order reaction with respect to the concentration of HI. A linear graph, the gradient of the graph of concentration versus time does not change, therefore a zero order reaction.

When using the syringes always keep them pointing downwards. This proved to be a curve – compare the blue rate data curve with the black ‘best straight line’ courtesy of Excel! Overall, these systematics and random errors do not influence the majority of the lab result as it continues to back up the collision theory and highlights the relationship between the rate of reaction and the concentration of the potassium iodide. The reation of kthe rate constant. It is the constancy of the half—life which proves the 1st order kinetics. How About Make It Original?

Its not a bad idea to repeat the calculation with another set of data as a double check!