• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Iodine Clock

Extracts from this document...


USING THE IODINE CLOCK METHOD TO FIND THE ORDER OF REACTION Apparatus: * Thermometer [0-110 �C] * Boiling tubes [10 cm3 �0.05] * Test tubes * Potassium iodine solution 1 mol dm-3 [15 cm3] * Potassium peroxodisulphate (VI) 0.04 mol dm-3 [10 cm3] * Sodium thiosulphate 0.01 mol dm-3 [10 cm3] * Starch solution [5 cm3] * Stopwatch [�0.5 s] Safety: Eye protection must be worn. Potassium peroxodisulphate (VI)- harmful and flammable Method: 1) First you are going to make up reaction mixture 1 from Table no 1, and measure how long it takes for the blue iodine-starch colour to appear. In each experiment use 2cm3 of sodium thiosulphate, 2cm3 of potassium peroxosulphate. Volume of each solution is 10cm3. To the first mixture add 5 cm3 of potassium iodide solution and do not add water. To second mixture add 4cm3 of potassium iodide solution and 1cm3 of distilled water. In third experiment pour 3cm3, in fourth 2cm3 and in the last one 1cm3 and add appropriate volume of water. ...read more.


Table3: The values of average time taken for the reaction to be visible and its uncertainty. Measurement Average Uncertainty 1 12.0 0 2 16.5 1.5 3 28.5 1.5 4 55.5 2.5 5 188.0 4.0 Rounded to 1 decimal place To determine the order of reaction using the iodine clock method, some of the calculation were necessary. At first, I calculated the [I-] concentration in each of 5 solutions using the equation: C[I-]= where VKI is the volume of KI solution [KI] is the KI concentration Vtotal is the total volume of solution On the example of 5th mixture: C[I-]= Table 5: The concentration of iodide in each solution Mixture Concentration of ions [mol dm-3] 1 0.5 2 0.4 3 0.3 4 0.2 5 0.1 Having calculated the concentration of [I-] ions, it is important to determine whether any reagent is in excess. To do that, I needed to calculate the concentration of iodide ions and the concentration of peroxodisulphate(VI) ions in mixture 5th. C[I-]= C[S2O3 2-]= It can be seen that the [I-] ions are in excess. ...read more.


The shape of the curve on the graph indicates that it is the reaction of first order. Conclusion and evaluation: The aim of the experiment was to find the order of the reaction using the iodine clock method. Using raw and calculated data I managed to determine its order and compare it with the literature. Rate of reaction and time in which it occured were necessary for the experiment. The graph showing the relationship between the iodide ions concentration and the rate of reaction was the key concept for establishing accurate order of reaction. The range of [I-] concentration was not very wide, but more than satisfying. The rate of reaction in the given range increases constantly but not directly proportional. The shape of the curve on the graph allow me to recognize the first order of reaction. Sadru Damji in "Chemistry 2nd Edition" present more accurate graph for the first order of reaction: rate [A]concentration As can be observed, the graph I created and that presented by Sadru Damji follows similar trend. My graph is not directly proportional, but its shape indicates it's a first order reaction. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our International Baccalaureate Chemistry section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related International Baccalaureate Chemistry essays

  1. Investigate the rate of reaction of luminol in various factors. The objective was to ...

    could be the human error or the equipment error, but they are less likely to happen; it could also be the characteristic of luminol. The best explanation could be the reaction of luminol does not affect by the temperature, it is because this is an oxidation, it does not necessarily require activation energy for the reaction to take place.

  2. Determining the activation energy of a reaction, By using the experimental data and the ...

    This is shown as follows: = -6368.5 -6368.5 8.31 -1 = 52900 Joules per mole (3sf)= 52.9 kilojoules per mole Where the gradient is measured over the range of 0.00310~0.00330 K-1. Uncertainties As with any experiment, uncertainties existed throughout this investigation.

  1. Rate of Reaction sodium thiosulphate

    Figure 1 was a graph plotted to show a relationship between concentration and time. The reaction showed a general trend that the time taken was shorter as the concentration increased because the gradient was negative. Unfortunately a curve had not been represented in this first order reaction.

  2. IB chemistry revision notes

    states that if a reaction can take place by more than one route, the overall enthalpy change is the same whichever route is followed. Enthalpies of Reactions * This is the energy change (heat) at constant pressure for any stoichiometric equation.

  1. Enthalpy Change Design Lab (6/6)How does changing the initial temperature (19C, 25C, 35C, and ...

    Using the other clean, dry 50.0 cm3 graduated cylinder, 40.0 cm3 of 1.00 mol dm-3 HCl(aq) were measured out. These 40.0 cm3 of 1.00 mol dm-3 HCl(aq) in the graduated cylinder were then poured into a clean, dry 150 cm3 beaker, and was labelled 'HCl(aq)'

  2. Aim: Using an iodine clock reaction to find the order of hydrogen peroxide and ...

    Pressure Controlled The experiments were all carried out at the same altitude. The pressure was 1 atm. Total Volume of Solution Controlled Since the solutions did not create 20ml each most of the time, the appropriate amount of water was added to a solution in order to make it equal 20ml.

  1. Research Question Find the rate expression for a reaction between propanone and iodine

    It can cause severe damage to the upper respiratory tract. * Wear a lab coat to avoid skin contact with chemicals Method In each experiment, the independent variable is the concentration of the substance which is being changed. The dependant variable is the rate of reaction, shown by the time taken for the solution to become colourless.

  2. The chemistry of atmospheric and water pollution.

    Replace CFCs with compounds which have significantly lower ozone depletion potentials (ODP) such as hyfrochloroflurocarbons (HCFCs). These compounds are effective as they are attacked while in the lower atmosphere thus it does not reach the stratosphere to attack ozone. However these compounds are more expensive and in some cases less effective than CFCs in various applications.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work