Sunday, August 4, 2019

Investigate how the change in concentration affects the rate of :: GCSE Chemistry Coursework Investigation

Investigate how the change in concentration affects the rate of reaction between sodium thiosulphate and hydrochloric acid Introduction I am trying to find out how the change in concentration affects the rate of reaction between sodium thiosulphate and hydrochloric acid. I predict that the higher the concentration of sodium of thiosulphate, the quicker the rate of reaction will be between the two substances. The scientific reason for my prediction is due to the collision theory. The collision theory is, that in order for chemicals to react they must come into contact with each other (collide). However, not all collisions result in chemical reactions as sometimes the particles just bounce off each other. The particles must have sufficient energy when they collide to react. If you increase the number of collisions, you increase the rate of reaction. Therefore, a higher concentration means a greater number of collisions. Diagram Preliminary Testing This is the word equation for the reaction between the two substances: Sodium + Hydrochloric Sodium + Sulphur + Sulphur + Water Thiosulphate Acid Chloride Dioxide Na2S2O3 + HCl NaCl + SO2 + S + H2O ( aq ) + ( aq ) ( aq ) + ( g ) + ( s ) + ( l ) Before I start the investigation, by having preliminary tests I can find a volume of each solution that I can use where I am able to complete the investigation in a reasonable period of time. When I am undergoing my experiment I will be making one variable. By changing the concentration of sodium thiosulphate, this is done by adding water to the solution. As I change the amount of water I put into the solution the concentration of it is changing. The more water that is put into the solution the weaker the concentration will become. To get my preliminary results I set up the experiment as above in the diagram section, and you use different amounts of the solutions. Use a burette to measure the amounts of the solutions needed, and put them into separate beakers. Using a funnel at the top of the burette to pout the solution into. After firstly using a measuring cylinder to measure the solution. Use a stopwatch to time how long it takes for the cross underneath the conical flask to disappear, as the solutions are mixed together. As the reaction turns the two colourless liquids, into a milky colour afterwards. Repeat the procedure with different amounts of the solutions, working out the best amounts that I could use for experiment. These are the results that I received: ------------------------------------------------------------------------ Amount of H2O Amount of sodium Amount of hydrochloric Time Taken

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