Disappearing Cross Experiment

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Disappearing Cross Experiment

Plan

====

I must produce a piece of coursework investigating the rates of

reaction. The rate of reaction is the rate of loss of a reactant or

the rate of formation of a product during a chemical reaction. There

are five different factors, which affect the rate of a reaction

(1) Temperature

(2) Concentration of a solution

(3) Pressure of gases

(4) Surface area of solids

(5) And catalysts.

I have chosen to investigate the effect temperature has on a reaction.

If I'd of had enough time, I would of done an experiment for

concentration of Hydrochloric acid to see what difference the rate of

reaction would be here. I wouldn't do pressure of gases, as most are

'invisible' to the human eye. I wouldn't do surface area of a solid,

as the two substances we are looking at are liquids. I wouldn't use a

catalyst in the experiment, because firstly I wouldn't know which

catalyst to use and secondly it may alter the outcome of the

experiment if used incorrectly.

· Aim

=====

To plan and carry out an experiment to discover how to change the rate

of reaction. The reaction being studied is between sodium thiosulphate

(Na2S203) and hydrochloric acid (HCl). The reaction I am using is:

Sodium Thiosulphate + Hydrochloric acid ->

Sodium Chloride + water + sulphur dioxide + sulphur

Na2S203 (aq) + 2HCl (aq) -> 2NaCl (aq) + H20 (l) + SO2 (g) + S (s)

· Equipment

[IMAGE]

· Diagram

· Method

1) With a piece of paper put on a bold cross, which is easy to see.

2) Put the conical flask on top of the cross with 20ml³of hydrochloric

acid.

3) Add 20ml³ of sodium thiosulphate into another flask and heat to

specific temperatures with the Bunsen burner (and using a

thermometer).

4) Once it is at the correct temperature, add it to the hydrochloric

acid and start the stopwatch.

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