Which are four factors affecting the rate of a chemical reaction and how do these affect the rate constant of the reaction?

For a chemical reaction to occur the reactant particles must collide with each other with the correct orientation and they must also have a minimum energy necessary for the molecules to successfully react, which is termed the "activation energy" of the reaction, E_a. The rate constant of the reaction is dependent on the E_a of a reaction and it is defined by the Arrhenius equation as k = Ae^(-Ea/RT), where A is the frequency factor (a constant) and e^(-Ea/RT) expresses the fraction of molecules in the reaction mixture which have energy equal or greater than the E_a (note: R = gas constant, T = temperature in K).An temperature increase will lead to increased kinetic energy of the reactant molecules so that a greater proportion of these will have energy equal or greater than the E_a, allowing for more successful collisions, therefore increasing the rate of reaction. As T is a determinant of k (as defined by the Arrhenius equation), k increases as temperature is increased. The addition of a catalyst to the reaction also increases the rate of reaction by reducing the E_a of the reaction by providing a lower-energy alternative route for the molecules to react. This will also affect k: as the E_a is lowered, k increases. Increasing the concentration of reactants will lead to more molecules and therefore to a greater number of successful collisions, speeding up the reaction; k will be left unchanged, as it doesn't depend on concentration. Lastly, increasing the surface area of the reacting compounds (for example breaking down blocks into pieces/powder) will also result in greater molecular contact and therefore more frequent successful collisions, also speeding up the reaction; again, k will not change.