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

An investigation into a factor affecting the rate of reaction of sodium thiosulphate (Na2S2O3) and hydrochloric acid (HCl).

Extracts from this document...


CHEMISTRY An investigation into a factor affecting the rate of reaction of sodium thiosulphate (Na2S2O3) and hydrochloric acid (HCl). Aim: I aim to investigate how altering the concentration of sodium thiosulphate will affect its rate of reaction with hydrochloric acid. The sodium thiosulphate (before dilution) is at a concentration of 40g/litre of water, and the hydrochloric acid is at 1M (1Molar). 1M designates a solution containing 1 mole of solute per litre of solvent. A mole is the molecular weight of a substance expressed in grams. I will probably use concentrations ranging from 100% to 10% in my experiment, and will repeat each concentration at least twice in order to obtain an accurate and representative average. Scientific Theory: When Na2S2O3 and 2HCl are mixed together, a yellow precipitate of sulphur is produced. This is suspended in a solution of all the other products of the reaction, making the resulting solution opaque when the reaction is complete. The equation of the reaction is: 2Na2S2O3 + 2HCl ? S2 + 2SO2 + H2O + NaCl sodium + hydrochloric ? sulphur + sulphur + water + sodium thiosulphate acid dioxide chloride All rates of reaction are governed by the basic principles of the collision theory. This states that the rate of a reaction relies on how hard and how often the active particles collide with each other. In my investigation, I will alter the concentration of the sodium thiosulphate. ...read more.


I poured the sodium thiosulphate into the conical flask and added the hydrochloric acid, starting the stopwatch as I did so. I looked down through the mixture at the "X" on the card and stopped the stopwatch when I could no longer see it. When this reaction was complete, I rinsed out the flask and dried it off. I next poured out 45ml of sodium thiosulphate and added 5ml of water. Another 10ml of hydrochloric acid was then poured into its measuring cylinder. I decanted the sodium thiosulphate/water mixture into the flask and swirled it around to ensure it was mixed. I then repeated as for the previous concentration, stopping the stopwatch when I could no longer see the "X". I repeated this, using each different concentration. (Obviously I repeated each concentration twice, in order to obtain enough results to produce an accurate average.) Diagram: Safety precautions: I wore safety goggles so that if any chemicals were spilt they would not harm my eyes. Fair Test: In order that my results were as accurate as possible, it was necessary that I ensured I only changed one variable - concentration. I made sure that I used the same size and shape conical flask each time, so that the depth of the liquid was not affecting our decision about when the "X" was obscured from view. I also attempted to keep each experiment at the same temperature because I only wanted the concentration to change. ...read more.


There was no anomalous data to be found in my results, which is both bad and good, as it means I now haven't got much to write about. I possibly could have done the 10% concentration, but that would have taken too long, and it would take so long, that the point would distort the graph and make it difficult to compare the other concentrations with it. Also the issue of constant temperature would be a more pressing issue if I had had time enough to consider it! To extend my investigation I could have kept the sodium thiosulphate as it is and changed the concentration of the hydrochloric acid. However this would have been limiting as an extension as the results would have followed almost exactly the same theory as the one above. To improve on my experiment I could have done the following: * used a different conical flask for each repeat of each concentration (reason not done this time: not enough equipment) * used a new set of measuring cylinders for each repeat of each concentration (reason not done this time: not enough equipment) * extended the range of my concentrations, for example used 5%, 15% and 25% etc. (reason not done this time: not enough time) * used a light sensor (and other automated equipment) instead of just human eyesight to judge when the cross was no longer visible - light sensor would not entail the possibility of human error (reason not done this time: necessary equipment not available) ...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

    In my investigation I am going to look at how concentration affects the rate ...

    3 star(s)

    All collisions will make a reaction in the experiment but not all collisions are successful, the rate of reaction depends on the number of successful collisions per second, which is directly proportional. The two things that are colliding in the collision are the hydrogen ions from the acid and the thiosulphate ions.

  2. The Rates of Reaction Between HCl and Na2S2O3.

    Even including the anomalous results, this shows that the particle collision theory is correct. When the number of acid molecules are increased, there is an increased chance of having molecules that will collide with the right orientation so they bond.

  1. Investigating the effect of temperature on the reaction between Sodium Thiosulphate (Na2S2O3) and Hydrochloric ...

    In order to make a fair experiment the X should always be the same size and drawn with the same pen; ideally always the same X would be used. I will carry out the experiments at 5 different temperatures starting at 20�C, room temperature, and the 30�C, 40�C, 50�C and 60�C.

  2. Reaction between sodium thiosulphate solution (Na2S2O3) and dilute hydrochloric acid (HCl)

    As they travel faster there are more collisions in a given time therefore the reaction get faster as we raise the temperature.

  1. Free essay

    Close Your Eyes

    He laughed and I just shook my head. Dougie's not the greatest guy to turn to for advice but he was the only one around. "Ok Doug, joke over" I said seriously and Dougie stopped laughing "I know she's 17 and all but I really like her" I meant it and by the look on Dougies face he knew that I meant it to.

  2. Factors Affecting Enzyme Activity

    between the rate of reaction and the concentration of liver suspension as I predicted in my hypothesis. I have added a best-fit line to my graph to better show this trend. As I predicted the line is slopes upwards showing that as the concentration of liver suspension increases the rate

  1. Factors Affecting the Rate of Reaction between Hydrochloric Acid and Sodium Thiosulphate.

    I could change the temperature of my reactants to produce a graph of temperature vs. time taken for cross to disappear. * Surface area (Type ie concentration is controlled) - increasing the surface area increases the number of surface particles exposed.

  2. 'Carry out an investigation to determine a factor affecting the rate of digestion of ...

    I will lift the film out of the solution only when it is near to the end point defined by me and is the same for each experiment. I will know when the end point is nearing by the results of my preliminary experiment.

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