Fair Test
I will make sure that I measure all the solutions correctly, if I don’t it could cause me to have an inaccurate result.
When I measure solutions I will make sure I use different measuring cylinders, so that no traces of other solutions can affect the solution that I want to measure.
The marker and paper that I use will always be the same, because if I use a different marker each time, then one marker maybe easier to see than the other, so I could see a marker better than the other.
I will repeat the tests twice so that I get more accurate results.
I will keep the temperature the same, temperature can effect the rate of reaction so if I did the experiment in two different places my results wouldn’t be that accurate. I will use room temperature.
Possible Errors/Problems
One error that could occur is if I use the sodium thiosulphate and hydrochloric acid from different bottles, there could be different amounts of certain materials in there, so I will have to use the same bottle to ensure no problems, I will do this by finishing the tests in one lesson.
The light will have to kept the same so that the marked x can be seen clearly. If the lights are turned off then the x may not be able to seen clearly. So the lights should be left on throughout the experiment.
Safety
I will be wearing goggles and a lab coat during the duration of the experiment, so that I can’t harm myself. The goggles will protect my eyes from splashing, solutions and the lab coat will protect my body from the dangers of acid.
Throughout the whole experiment I don’t want to stand too close to the solutions just in case a dangerous reaction happens.
I will make sure all the equipment is set up appropriately and all the beakers are kept away from the edges of the work bench.
Last of all I will make sure that my bags and other property is kept well under the bench, so that it can’t cause me or the people around me any harm.
Prediction
I predict that the lower the concentration, the slower the reaction will take place. This is because there will be more sodium thiosulphate particles in the beaker when the sodium thiosulphate has a high concerntration. So there is a bigger chance of particles colliding, making the x disappear quicker, this prediction is based on my research on the collision theory.
Method Diagram
Higher Concentration Lower Concentration
= Sodium thiosulphate particles
= Hydrochloric acid particles
Readings
Method
- I drew a marker on the piece of paper, in pen.
- I put a conical flask on top of the marked paper
- I filled one beaker with sodium thiosulphate, one with water and one with hydrochloric acid
- I then measured out 50ml of sodium thiosulphate
- I used another cylinder to measure out 5ml of hydrochloric acid
- I added both the solutions into the conical flask.
- I started timing.
- When the solution had gone unclear so that the marker could not be seen, I stopped the watch and recorded the time
- I then repeated the experiment for all my other readings
- I then repeated it again.
Results
Here are the results I collected.
Conclusion
I have got my results (above), and I have decided that the best concerntration to use for my final experiment will be 20%. This reaction won’t happen to quickly.
Actual Investigation
Factors
Temperature
Surface area
Gas Reaction
Catalyst
Actual Reaction
The reaction that I will be using in my experiment will be as follows:
Sodium thiosulphate solution (l) + dilute hydrochloric acid (l) → sodium chloride (aq) + water (l) + sulphur dioxide (g) + sulphur (aq)
The solutions are both clear when not mixed, but when they are mixed the solution will get cloudy over time because sulphur is produced.
Variables
Dependant
The dependant variable is the time. The times will not change throughout the experiment. I will use a basic stop watch to find the time taken.
Independent
The independent factor is this experiment is the temperature of the solution, this will vary throughout the experiment.
Control
I will use the same amount of solution in this experiment and that is 55ml. The sodium thiosulphate and hydrochloric acid will have the same concentration throughout the experiment.
Errors
I will be doing the experiment over more than 1 lesson, so the equipment and solutions I will use will not be exactly the same. Even the room temperature will change due to people entering and exiting the room.
Fair Test
I will make sure that I measure all the solutions correctly, if I don’t it could cause me to have an inaccurate result.
When I measure solutions I will make sure I use different measuring cylinders, so that no traces of other solutions can affect the solution that I want to measure.
Before the experiment takes place I will take down the room temperature, so that I can get the thermometer to return to the room temperature each time before re-using it.
The marker and paper that I use will always be the same, because if I use a different marker each time, then one marker maybe easier to see than the other, so I could see a marker better than the other.
Equipment
- Stopwatch
- Hydrochloric Acid
- Sodium Thiosulphate
- Bunsen Burner
- Gauze
- Mat
- Tripod
- 3 Measuring Cylinders
- 3 Beakers
- Conical Flask
- Goggles
- Lab coat
Safety
I will be wearing goggles and a lab coat during the duration of the experiment, so that I can’t harm myself. The goggles will protect my eyes from splashing, solutions and the lab coat will protect my body from the dangers of acid.
Throughout the whole experiment I don’t want to stand too close to the solutions just in case a dangerous reaction happens.
I will make sure all the equipment is set up appropriately and all the beakers are kept away from the edges of the work bench.
The Bunsen burner can cause damage if used incorrectly. The safety flame should be put on when not heating a solution.
Hot objects i.e. tripod should be left to cool down, as they can cause burning when hot.
Make sure gas tap is turned off when not in use.
Last of all I will make sure that my bags and other property is kept well under the bench, so that it can’t cause me or the people around me any harm.
Prediction
I predict that as the temperature is increased, the rate of reaction will also increase.
The temperature can cause major changes within the results, if the heat increases then the particles will overtake the activation energy.When the temperature increases the particles will have more energy and move faster. So they will collide more often. Particles that have more energy will be able to overcome the activation energy barrier. So particles will collide more frequently.
If the concentration of a solution increases then there are more reactant particles per unit. This increases the chance of reactant particles colliding with each other.
When the pressure increases within a gas, the particles are pushed closer together, this process increases the rate of reaction, and the concentration
For a reaction to occur particles have to collide with each other. Only a small minority result in an actual reaction.
Method
- I drew a marker on the piece of paper, in pen.
- I put a conical flask on top of the marked paper
- I filled one beaker with sodium thiosulphate, one with water and one with hydrochloric acid
- Measure 10ml of sodium thiosulphate in a measuring cylinder
- Measure 40 ml of water in another measuring cylinder.
- Pour the water and sodium thiosulphate in the conical flask
- Put a thermometer into the solution
- Measure 5ml of Hydrochloric Acid
- heat the sodium thiosulphate solution until it reached just under the first temperature
- Take the conical flask and place it on the marked x
- Add hydrochloric acid
- Time reaction
- Once the x disappears, stop the stop watch and record the time
- Change the temperature of the first solution and heat it
- Repeat this twice
Diagram
Results
Analysis
The results that I collected look accurate, as there are none out of place. So I am happy with the outcome of them.
My prediction was: I predict that as the temperature is increased, the rate of reaction will also increase.
The results above show that the higher the temperature the quicker the reaction and then the lower the temperature the slower the reaction.
My graph shows that when the temperature decreases the time taken increases. This shows that the higher the temperature of the sodium thiosulphate solution, the quicker it reacts with the hydrochloric acid
So my prediction was correct, as I stated earlier its connected with the collision theory. Before we can get a chemical reaction, particles crash together. They must collide. So this is the collision theory.
Evaluate
Overall I was happy with the outcome of my experiment, the results seem accurate and the experiment went well. I Fell my graph reflects the good outcome of this experiment. I also feel the experiment went well time wise, I managed to finish the experiments with a lesson left over, giving me time to prepare my write up.
I was happy that my final prediction was correct because I feel as if it shows that I know what I’m doing. My prediction was based on the collision theory.
I set out the preliminary work really well, and that reflected on my final experiment. The preliminary work was handy because it gave me more time to understand the rate of reaction, it also gave me more time to plan my final experiment which was useful.
To have made my final experiment better I feel I could have done the test more times, so that I would get a more accurate average result, but I was happy with the results I already had so I felt this was un-necessary.
I could have also done the same experiment but changed the temperature, this would have been interesting to see how the results would vary. I think that they would vary a lot because temperature can increase or decrease the rate of reaction massively.
I followed all the safety rules that I put down in my preliminary work and final experiment work, this is always going to be important because I didn’t want anyone to get harmed. I used all the help sheets provided to make sure that I was doing all the necessary procedures correctly.
I repeated the test 3 times so that I could get good average results. If I had another chance I would have done the experiments all on the same day, but as I stated early unfortunately time wasn’t on my side completely.
To ensure that I got all the measurements right I had to keep re-measuring the solutions, it was time consuming but it was worth it, the results I have reflect that, I also always got a second opinion, so I could be sure that I was using nearly the perfect amount.
If I had to extend this investigation I feel it would be most interesting if I changed the actual surrounding temperature, I could do the experiment in the class and outside, seeing how the surrounding environment affects the rate of reaction.
