• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month
Page
  1. 1
    1
  2. 2
    2
  3. 3
    3
  4. 4
    4
  5. 5
    5
  6. 6
    6
  7. 7
    7
  8. 8
    8
  9. 9
    9

Sodium Thiosulphate coursework.

Extracts from this document...

Introduction

GCSE Chemistry - Sodium Thiosulphate coursework Preliminary Study I am going to investigate the rates of reaction, and the effect different changes and factors have on them. The rate of reaction id the rate I lose a reactant or the rate of formation of a product during a chemical reaction. The rate of reaction is measured by dividing 1 by the time taken for the reaction to take place. There are five factors that affect the rate of reaction; these are - temperature, concentration (of solution), pressure (in gases), surface area (of solid reactants) and catalysts. I have chosen to investigate the effect concentration has on a reaction, the reason being because this is practical to measure. Aim To see the effects of changing the concentration of Sodium Thiosulphate has on the rate of reaction. Here is the word and symbol equation (balanced) of my investigation: Sodium Thiosulphate + Hydrochloric acid --> Na2S2O3(aq) + 2HCL(aq) --> Sodium Chloride + water + sulphur + sulphur dioxide 2NaCl(aq) + H2O(l) + S(s) + SO2(g) My investigation is going to be done by varying the concentration of Sodium Thiosulphate (while everything else remains constant). I chose this one because it is soluble in water, as the other is as well. Also, Sodium Thiosulphate is available in larger amounts as well as the concentration being prepared already. These are the concentrations of Sodium Thiosulphate I will be using first: - 0.5 mole/dm3 of HCL (This will stay the same. It is a Dependant variable). 0.5% - 2.5% of Sodium Thiosulphate (All the concentrations will be tested in turn going up in steps of 0.5%. This is an Independent variable). ...read more.

Middle

Powders react faster than blocks - greater surface area and since the reaction occurs at the surface we get a faster rate. This factor does not apply to my investigation. 4: The presence (and concentration/physical form) of a catalyst (or inhibitor). A catalyst speeds up a reaction, an inhibitor slows it down. This factor can be named an Independent variable as I can add a catalyst, but I will not be doing so. 5: Light. Light of a particular wavelength may also speed up a reaction. E.g. alkanes reacting with Halogens. Light can be names a Dependant variable, as I have no control over the wavelength of light. I've used the term reaction rates, so I should define what we mean by this; the reaction rate is the increase in molar concentration of product of a reaction per unit time or the decrease in molar concentration of reactant in unit time. Rate Law and Reacting Order If we examine the effect on the rate of a reaction by changing the initial concentration of reactants, we may be able to derive the rate law and hence the reaction order. Consider the following reaction: - 2NO2 + F2 --> 2NO2F If the concentration of NO2 is doubled then the rate is doubled, likewise when the concentration of the fluorine is doubled the rate doubles and so we get the following rate law; Rate = k [NO2][F2] The rate law is an equation that relates the rate of a reaction to the concentration of reactants raised to various powers. The rate constant, k, is proportionally constant in the relationship between rate and concentrations. This has a fixed value at any given temperature but varies with temperature. ...read more.

Conclusion

The total amount of moles reacting per second is shown above. Fig. 7 shows that when the concentrations were relatively low (0.5M - 1.0M), the increase of rate x 1000 was also fairly small (increasing from 5.1 to 6.7). There was then a gradual increase in the difference, and between 1.0M and 1.5M the rate more than doubled from 6.7 to 10.2 compared to previous results. This shows that there are far enough collisions at 4.5M than at lower concentrations. For this to make sense, it is necessary if I recap on the collision theory: For a reaction to take place, particles must collide with each other, only a small percent result in a reaction. This is all due to the energy barrier to overcome. Any particle with enough energy to overcome the barrier is called the activation energy, or the Ea. The size of this activation energy is different for different reactions. If the frequency of collisions is increased, the rate of reaction will increase. However, the percent of successful collisions remains the same. An increase in the frequency of collisions can be achieved by increasing the concentration, pressure, or surface area. Like stated previously, most of the results that had been recorded didn't fit the line-of-best-fit. Which could be a result of inaccurate calculation, temperature or even the concentration levels. Looking at the curve on fig.3, it shows the intake of heat energy that results in a faster reaction time - this supports the fact that this reaction is an endothermic reaction and when heat energy is absorbed, the time taken decreases substantially. However, it seems that the HCL had reached its factorial limit, which would have affected the time recorded - therefore, higher concentrations should have been used. This is proved when the results slope horizontally on fig. 3 & 6. Graham Black 11CE Alsop High School ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our GCSE Patterns of Behaviour 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 GCSE Patterns of Behaviour essays

  1. Marked by a teacher

    Rate of Reaction Chemistry Coursework

    4 star(s)

    Collect the jar and delivery tube and stick one end of the delivery tube up the end of the burette, this has to be done quickly- We do this as this is where the gas from the reaction goes up and it goes through the delivery tube and will

  2. The aim of the investigation is to examine the kinetics involved in the reactions ...

    These will in turn slower the rate of the reaction. This is called crowding effects. Using 10 cm3 of 2 molar acids Number of moles = (volume/ 1000) x concentration = 10/1000x 2 = 0.02 moles of acid Ratio of acid to Mg = 0.02: 5.8 x 10-4 = 34:

  1. Exothermic and endothermic reactions

    Helium is at the top of group 0, and so must be the noble gas with the lowest boiling point. Question 6 Identify a metal, M, which forms a chloride with the formula MCl2. The Answer Mg (magnesium). Examiner's Note Well done! The two possible correct answers are Mg (magnesium)

  2. Reactivity of the Alkanes

    + 9O2 (g) 7H2O (l) + 6CO2 (g) In this reaction hexane is heated in the atmosphere and burnt, reacting with oxygen. This releases carbon dioxide and water. This reaction is very harmful to the atmosphere. That's why there is so much trouble with pollution and carbon dioxide levels rising as a result of burning fossil fuels.

  1. Find out how the rate of hydrolysis of an organic halogen compound depends on ...

    The cross is no longer visible when a certain amount of sulphur has formed. The reaction time to reach this point can be measured using different starting concentrations of sodium thiosulphate solution. The volume of each solution and the concentration of the hydrochloric acid must be kept constant in each experiment.

  2. Enzyme Coursework.

    Method Apparatus: � two syringes � large beaker of water � conical flask � bung � delivery tube � syringe tube � 20 volume Hydrogen Peroxide solution � 20 volume yeast suspension solution � two small conical flasks � stop watch � 'V' shapes glass tube or oxygen output �

  1. Free essay

    Close Your Eyes

    she said brightly as I opened the door. "Hey" I stepped aside and she walked in "So, did you find me alright?" I asked making casual conversation. "Ha! No, I got lost about 5 times which is the reason I'm late by the way.

  2. Sodium Thiosulphate Coursework

    The experiment is repeated with all the concentrations. The whole procedure is then repeated. Experiment 2 - Changing the temperature 5 cm of HCl (at concentration 1 mol./dm3) and 15 cm of sodium thiosulphate (at varying concentrations - 10 to 35 g/dm3) are poured out into two measuring cylinders.

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