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Catalysts.
Catalysts are chemicals that speed up a chemical reaction but are not used up. Catalysts increase the rate of reaction because it provides an alternative route for the reaction by lowering the activation energy needed. .
Stirring.
Stirring the solution once mixed together or shaking it can cause the rate of reaction to increase because it will increase the kinetic energy of the molecules and there will be more random, frequent, forceful, and more successful and fruitful collisions rate.
Changing the pressure in a gaseous reaction:.
This factor is not relevant for this investigation since the reactants are not in a gaseous state. In reactions which involve gases, increasing the pressure makes the reactant particles more crowded. It increases the density so the number of molecules of a reactant per unit of volume increases resulting in more collisions therefore increasing the rate of reaction.
Changing the surface area of solid reactants".
This factor is also not relevant for this investigation since the reactants do not involve any solids. In reactions which involve solids, the greater the surface area the faster the rate of reaction because increasing a surface area of a solid reactant will expose more of its particles which allow more collisions to take place. .
There are various ways of measuring the rate of reaction: .
Collecting and measuring a gas product. .
However this can be very difficult to measure for this particular reaction because the gas produced in the reaction is Sulfur dioxide which will react with oxygen and react with the solutions to produce acid rain, which will dissolve in the solution, preventing me from collecting the volume of gas formed. This is also the reason why the gas bubbles aren't visible during the reaction. .
Recording the mass of the reaction at regular intervals of 30 or 60 seconds:.
The rate of reaction for this method can be expressed by the rate of loss in mass from the flask, which is proportional to g/min based on the initial gradient (picture above).