Investigating Rate of Reaction

Investigating Rate of Reaction

I will be studying the rate of reaction between sodium thiosulphate

and dilute hydrochloric acid.

I believe that if I increase the concentration of the sodium

thiosulphate, the rate of reaction will increase, because the

molecules are closer together, so there are more collisions per

second.

I believe if I double the concentration of the sodium thiosulphate

then the rate of reaction will double, because there will be twice as

many sodium thiosulphate molecules in the same area, and so there will

be twice as many collisions.

Using the method on the briefing sheet I carried out preliminary

experiments using measuring cylinders. The times taken for the cross

to disappear are shown bellow:

Vol. of Thiosulphate/cm

Vol. of H O/cm

Time/Sec.

50

0

39

10

40

208

This seemed to be a reasonable range of reaction times so I will study

this range of concentrations.

Method:

Apparatus: -Safety Goggles

-Burette

-Conical Flask

-Measuring Cylinder

-Thiosulphate

-Dilute Hydrochloric Acid

-Water

-Stop Watch

1. Wear safety goggles at all times during the experiment. The

chemicals being used are at low enough concentrations that they are

only dangerous if they get in your eyes and so safety goggles prevent

any risk.

2. Draw a black cross on a plain, white piece of paper and place the

conical flask on it. When the reaction begins the solution will be

clear, when it has finished the solution will have become clouded so

it is no longer possible to see through it. Therefore when the cross

is no longer visible the reaction has finished.

3. Using the burette accurately measure 10cm of hydrochloric acid and

pour it into the conical flask.

4. Using the burette accurately measure 50cm of thiosulphate and add

this to the conical flask.

5. The thiosulphate will immediately begin reacting with the acid;