how reaction rate varies with sodium thiosulphate

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How reaction rate varies with sodium thiosulphate concentration Background information
Sodium thiosulphate and hydrochloric acid are both colourless liquids, when the two reactants are reacted together they produce sulphur. The sulphur that is produced from the reaction changes the solution to yellow and cloudy, this is a precipitation reaction, where a two solutions react and a solid forms in the solution, the solid is said to precipitate out. Some reactions will occur quickly such as fireworks exploding or an apple slowly turning brown. Sodium thiosulphate and hydrochloric acid react together according to the word equation below. Hydrochloric acid+sodium thiosulphate->sodium chloride + sulphur dioxide + sulphur + water Formula

Na2 S2 O3 (aq) + 2Hcl (aq) -> 2Nacl (aq) H2o (L )+ So2 (g )+ S2 (s) Introduction
This investigation will be carried out in order to discover how the concentration of sodium thiosulphate affects the rate of reaction with hydrochloric acid. This reaction occurs due to successful collisions between particles of reactants. Collision theory helps to explain how a chemical reaction occurs, collision theory states that atoms ions and molecules must collide with each other with the correct orientation and the correct amount of activation energy in order for a reaction to occur, if they do not collide with sufficient activation energy Ea they will just bounce back of each other. The activation energy is the minimum amount of energy required to form an activated complex. An activated complex is the transition state molecule, with some bonds partially broken and new bonds partially formed, it is therefore a temporary arrangement which may form products or break apart to form reactants. Activation energy is needed to break the initial bonds in order for new bonds to form. Increasing the concentration of a reactant accelerates the reactions in which they are involved, to react a particle must first collide, and so increasing the number of particles in a given volume will increase the number of collisions. Collision theory also helps explain why increasing the pressure under which gaseous reactions take place increase the rate of the reaction, this happens because when the pressure is increased the gasses become more concentrated. If the temperature is changed in a reaction and increased the particles will gain more kinetic energy and move around alot more quickly and therefore have more successful collisions per second. Only a small temperature increase can lead to a large increase in the rate at which the reaction occurs, for every 10oc rise the reaction rate will approximately double. Rate of reaction can also be increased by increasing the surface area of the reactant, a large solid will have a small surface area in comparison to the amount of reactant molecules that the solid contains, it is only the reactant molecules on the surface of the solid that will be able to have successful collisions with other molecules, though if the solid is ground down into a fine powder then many more molecules are available for effective collisions. A catalyst provides an alternative route for a reaction to take place, the effect that a catalyst has on a reaction rate is to lower the activation energy and therefore increase the rate of reaction, to explain this in terms of collision theory, if the activation energy is lowered a greater proportion of molecules have sufficient energy to make effective collisions . A catalyst will not be used up in the process of the reaction in which it is used. A reaction is a chemical process in which two particles (reactants) join to form a new product or products, a reaction is measured by how fast or how slow in a single unit of time the reactants react to form products, the speed at which a reaction occurs can be monitored by the amount of reactant used up in the reaction per unit of time or the amount of products that are formed per unit of time. If the solution that is...
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