When Sodium Thiosulphate and dilute Hydrochloric acid react they produce a cloudy precipitate. The chemicals are both clear solutions and will react together to form a yellow precipitate of Sulphur.

Authors Avatar

Theory

When Sodium Thiosulphate and dilute Hydrochloric acid react they produce a cloudy precipitate. The chemicals are both clear solutions and will react together to form a yellow precipitate of Sulphur. The equation for this is;

Na2S2O3 + 2HCl                      2NaCl + SO2 + S + H2O

As the solution turns cloudy we can observe the rate of reaction by placing a red cross under the beaker and seeing how long it takes for it to disappear.

There are various factors that could affect this experiment, this are, time, concentration and temperature. I don’t think surface area will be a factor as both chemicals are in liquid form.

In my experiment I will be changing the concentration.

I think that as the concentration of the Sodium Thiosulphate gets greater the time taken for the cross to disappear will become shorter. This is because in order to react with each other the two particles must be in direct contact. With the lower concentrations there will be less particles and they will be spread around more and be further apart meaning that they will meet less often and reactions will happen less. In the higher concentrations there will be more particles and they will be closer together thus more likely to hit into each other.

Join now!

Not all of these collisions will result in a reaction though. The reactions will only occur if the particles have enough activation energy (Ea). This energy enables the chemical bonds to be broken and the atoms, ions and electrons to be rearranged.

Equipment

  • Flask
  • Measuring Cylinder
  • Stop-Watch
  • White Paper
  • Red Pen
  • Pipettes
  • Safety Glasses

Procedure

  • Wash all the equipment carefully
  • Measure out 50cm³ of Sodium Thiosulphate into the flask
  • Measure out 5cm³ of dilute ...

This is a preview of the whole essay