Factors that Affect the Rate of a Chemical Reaction

Factors that Affect the Rate of a Chemical Reaction

I am going to plan and carry out an investigation into one factor that

affects the rate of a chemical reaction. That chemical reaction is

going to be between sodium thiosulphate solution and dilute

hydrochloric acid. To make this a fair test we will have to keep all

variables the same except the one we area investigating. My variable

that I am going to investigate is going to be the concentration of the

sodium thiosulphate.

Sodium thiosulphate solution and dilute hydrochloric acid produce a

solid (seen as cloudiness). I am going to time how long it takes for

the solid to block out a cross underneath a conical flask. From the

time taken I can calculate the rate of reaction by working out 1/time

(units s-1).

Variables

The variables that may have an affect on this experiment are:

· The amount of sodium thiosulphate - the more sodium thiosulphate the

more it is in contact with the acid so it will react at a different

speed. I am going to be changing the concentration of this.

· The concentration of the Hydrochloric acid - this is the proportion

of hydrochloric acid in the solution.

· The volume of acid - this is the amount of acid used to react with

the sodium thiosulphate.

· Temperature - adds energy to the reaction and can therefore speed up

the reaction

· The cross - has to be the same amount to be a fair test, if the

cross was not the same size each time then the results could be

different

· Residue after each experiment - if the residue builds up it could

block visibility on the next experiment.

Prediction

I predict that the higher the concentration the faster the reaction

will take place this is because in a higher concentration there will

more hydrochloric acid molecules per set volume. This means that there

will be a higher chance of the sodium thiosulphate molecules colliding