Equipment
1x Stop watch
1x Conical flask
1x Paper with black cross
1x 100cm³ Measuring cylinder
1x 10cm³ Measuring cylinder
1x Goggles
1x 100cm³ beaker
1x 10cm³ beaker
350cm³ of Sodium Thiosulphate
120cm³ of Hydrochloric Acid
190cm³ of Distilled Water
Safety
- Must wear goggles during the experiment
- Must tie long hair back
- Safety cards must be on a wall
Hazards
1) Dilute hydrochloric Acid Irritant and corrosive if any spilt wash with water
2) Sodium Thiosulphate Flammable and irritant corrosive if any spilt wash with water
Equation
Na2s2o3 + 2HCL 2NaCL + H2o + S +SO2
Back ground knowledge
From researching in textbooks (Gcse chemistry) and the Internet I found out that: for a reaction to take place the particles must collide together. On top of that both particles must have enough energy to react.
1) 2) 3)
Water particles
Hydrochloric acid
Magnesium
- In a liquid the particles move round freely. An acid particle is about to collide with the magnesium.
- If the two particles have enough energy there will be a reaction. This will make magnesium chloride and hydrogen.
- If the two particles don’t have enough energy to react they will just bounce and move in opposite directions.
If the I change the concentration of the acid is increased the it would look like this:
1)
In this one there are more water particles than acid particles. So this that there is not much chance of the acid colliding with the magnesium. It is less concentrated.
2)
In this one there are more acid particles. So it is more concentrated. As there is more acid there is a higher chance of a reaction.
Prediction
I predict that as the concentration gets greater the slower the reaction will take for example 50cm³ of Thiosulphate and none of water it should be very quick and if it is 10cm³ of Thiosulphate and 40cm³ of water should take a very long time.
Results
From the results I can say that my prediction was correct. The higher concentration was the slower the reaction became. If you look at the graph with is on the separate sheet of paper you will see that the first two readings it took were nearly in a horizontal line. This meant they were quick, this would be because the concentration of the Thiosulphate was very low. When the solution got more concentrated the time s became longer for example 10cm³ of Thiosulphate and 40cm³ of water the time was 183 seconds. This relates well to my background knowledge I found out that the higher the concentration was the slower the reaction would be this clearly happened in my experiment. Once the solution of Thiosulphate had gone under 20cm³ the reaction time was considerately longer.
Average reaction time
Evaluation
The experiment was under control at all time there were unexpected results. The results from the experiment did match my prediction, the reaction time did get longer when the concentration got larger. In my experiment they’re not any anomalous points. Everything went to plan, there were no problems. I could have made the experiment better by using better and more exact measuring cylinders. I could have altered the experiment by changing the temperature to see if the temperature varies the reaction time. I could have improved the experiment by tacking reading every 5cm³ instead of every ten like I did. This would have given me a wider range of results so it would have been more accurate. From this experiment I have found out that if you change the concentration of Thiosulphate it will increase the time it reacts in. This experiment could have been done with temperature and it could have changed the reaction time.
Sir I am not too happy with my final version so when you mark it could I have it back to improve and hand again please.