Concentration And Reaction Rate :: essays research papers

How concentration affects reaction rate. The aim of this investigation is to see how the concentration of a reactant in ratio to the reactor affects the rate of a reaction. When hydrochloric acid and Thiosulphate react together sulphur is liberated this means that as the reaction goes on the solution will become yellow and will change from being transparent to translucent to opaque. The sulphur is formed as a solid but not in the usual precipitation way. Na2 + S2 + 2HCL 2NaCl+SO2 + S2 +H2O To time the reaction I will draw a black cross on a piece of plain paper on which the beaker of reactants will be placed (HCL and Thiosulphate). When the chemicals come into contact with each other I will start timing with a stopwatch and will stop timing when the cross is longer visible through the beaker from above. A reaction: A chemical reaction between to chemicals can only happen if their molecules can collide into each other. Out of many collisions there will be a few successful collisions, which means that the two molecules will exchange electrons and that means that they have reacted. These molecules have to hit each other in the right direction and at the right speed; in short the rules for a â€Å"successful collision† are specific and complex. But if the number of collisions per second increase so will the number of successful collisions increase. This means that the rate of the reaction has increased. For a reaction to occur you also need the required activation energy which means that if there isn’t enough the reaction won’t take place although catalysts can lower this. Input Variables: Catalyst Concentration of acid or thiosulphate Temperature Light Temperature: If you increase the amount of energy in a group of molecules the reaction rate will increase. When you give energy to molecules they tend to move about a bit more. And this means that if they are moving rapidly from place to place they are going to have a lot more collisions and because they are having lots of collisions the chances are that they will have a successful collision a lot more quickly than if they weren’t. This basically means that reaction rate is increased as temperature increases. I believe that temperature is directly proportional to reaction rate. As you can see the graph is partly true to the above statement but gradually starts to curve off, this is because at a point the intense temperature will start to boil the liquids which means they will start to evaporate and concentration will be affected.