The effect of temperature on rates of reaction

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I intend to investigate if the rate of a chemical reaction changes as

the temperature increases.

There are many other variables, which can be changed in some way to

effect the reaction, some are listed below: -

- Volume of Sulphuric acid

- Concentration of Sulphuric acid

- Initial temperature of Sulphuric acid

- Motion of liquid (speed of stirring) if concentration of acid is

studied

- Amount and size of magnesium

- Purity of magnesium

- The extent of oxidation on the surface of magnesium

- Addition of catalysts

- Size of container

- Temperature of surrounding environment

- Pressure at which reaction is conducted

- Insulation of the beaker where experiment takes place

- Height of thermometer above the base of the beaker

Whilst studying the rate of reaction according to the temperature, in

this experiment I predict that the rate of reaction will increase as

the temperature increases. This is because when two chemicals react,

their molecules have to collide with each other with sufficient energy

for the reaction to take place. This is collision theory. The two

molecules will only react if they have enough energy. By heating the

mixture, you will raise the energy levels of the molecules involved in

the reaction. Increasing temperature means the molecules move faster.

This is kinetic theory. For example, a more detailed hypothesis could

be that if I double the temperature, the rate of reaction will double

as well (e.g. 20 c has a reaction time of 10 seconds whist

40 c has a reaction time of 5 seconds)

Here are diagrams to demonstrate the kinetic and collision theory.

Apparatus

Magnesium ribbon

40cc sulphuric acid

Beaker

Measuring cylinder

Thermometer

Tripod

Gauze

Heat Mat

Bunsen Burner

Stopwatch

Method

To begin the experiment I will measure out 40cc of sulphuric acid into

a measuring cylinder and then pour it into a beaker. I am not certain

how much magnesium to use that will best react with 40cc of sulphuric

acid. So before I start the final experiment I will carry out a

preliminary test to discover whether a 2cm, 3cm, or 4cm accurately

measured piece of magnesium ribbon is most efficient when doing the

final experiment.

Once I have picked the amount of ribbon to use I will place the 40cc

of acid into the beaker, onto a gauze and tripod and over a heat mat.

I shall then warm the acid up with a Bunsen burner placed underneath

the tripod until the temperature reaches 20 degrees centigrade

(measured by a thermometer) and then drop the previously measured

magnesium ribbon into the warmed acid and start timing it the second

it drops in, until it completely vanishes to the eye because it has

stopped reacting and has in a way 'dissolved'.

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