Factors that Influence the Rate of a Chemical Reaction

Factors that Influence the Rate of a

Chemical Reaction

Aim

The aim of this experiment is to find out what affects the rate at

which a reaction occurs between sodium thiosulphate and hydrochloric

acid. I want to find out whether and to what degree varying the

concentration of sodium thiosulphate has any effect on the rate of

reaction.

Prediction

I predict that the greater the concentration of Sodium Thiosulphate

solution the faster the chemical reaction will take place. I think the

concentration of a solution affects the rate of reaction because:

'The rate of reaction depends on how frequently the molecules of the

reacting substances collide. A more concentrated substance has more

molecules with a set volume than one which is more dilute one. This

means because there are more molecules about, the frequency of

collisions is greater and the reactions happen faster.'

Method

To find out what effect the concentration has on the rate of reaction,

I will be measuring the time it takes for the reaction to complete

when various different concentrations of sodium thiosulphate are used.

From my preliminary experience in these kinds of reactions I know the

mixture will turn cloudy, so I will use this as a measure of how much

they have reacted.

For this experiment I will presume that when the mixture has clouded

enough so that I can no-longer see the cross beneath it, the reaction

is complete.

Also from my preliminary experiments I know the appropriate

measurements to use, so that the time span of each test is not too

quick, so that it is not difficult to measure and is not too long so

that it wastes a lot of time.

1. Firstly set up the equipment (as in the diagram).

Measure out 20mls of hydrochloric acid into one measuring cylinder.

2. Next measure out 20mls of sodium thiosulphate.

[In this instance we are not diluting it]

3. Empty the hydrochloric acid into the conical flask and as you tip

the sodium thiosulphate into the same conical flask, start the stop