Preliminary test:
The reaction taking place is sodium thiosulphate with hydrochloric acid in different temperatures. I am using different molars as I want to test which one would make the solution react faster, but also prove that the higher the temperature, the faster the reaction, and vice versa as stated in my prediction. I don’t want the temperatures to increase/lower to room temperature, as it wouldn’t prove much. Therefore, looking at my preliminary test, the molar used will be 1 for my actual experiment.
Collision Theory when particles are heated:
Fair test:
I will be keeping all the factors that affect the rate of reaction the same except for temperature, as the effect of temperature is what I want to investigate. I will only use 40cm³ of sodium thiosulphate and 10cm³ of hydrochloric acid. I will control surface area through using liquids as the reactants, and also, the molar will be kept at 1. I am keeping this test fair as neither concentration, surface area or volume is changed.
Safety Procedures:
In this experiment, we shall be using Hydrochloric Acid, which is potentially extremely harmful if it comes in contact with the body. Hydrochloric acid is a corrosive, poisonous liquid, which may be fatal if swallowed or inhaled. Also, inhalation may cause lung damage.
- Inhalation of vapours can cause coughing, choking, inflammation of the nose, throat, and upper respiratory tract, and in severe cases, pulmonary oedema, circulatory failure, and death.
- Swallowing hydrochloric acid can cause immediate pain and burns of the mouth, throat, oesophagus and gastrointestinal tract. May also cause nausea, vomiting or diarrhoea. Swallowing may be fatal.
- Can cause redness, pain, and severe skin burns. Concentrated solutions cause deep ulcers and discolour skin.
- Vapours are irritating and may cause damage to the eyes. Contact may cause severe burns and permanent eye damage.
Due to the fact that Hydrochloric acid is a highly dangerous substance, I shall be wearing aprons to protect clothing, gloves to protect my hands, and goggles to protect my eyes.
Equipment:
- Hydrochloric Acid
- Sodium Thiosulphate
- Water baths
- Measuring cylinder
- Safety equipment (goggles, apron, gloves)
- Water
- Ice
- Stopwatch
- Conical flasks
- White tile (marked with an X)
- Boiler
- Thermometer
Method:
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Assemble equipment
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Boil water and collect ice from fridge
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Put water and ice separately in water baths
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Put the containers of Hydrochloric acid and Sodium thiosulphate in the water baths to reach their temperature
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Measure the temperature with a thermometer
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Take out the containers and measure 40cm3 of sodium thiosulphate and 10cm3 of hydrochloric acid and put into conical flasks
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Put conical flask above white tile with cross
- Measure how long it takes for the cross to disappear from the sulphur precipitate forming from the reaction
- Record in a table
Science Coursework: Rates of Reaction
Skill section O
Introduction:
Now that I have performed the experiment and gathered my results, I will show you the 3 sets of results and the final average results in a table. I will also say what safety procedures were taken. I will comment on any anomalies that may have occurred in my results and also talk about any changes or difficulties which took place as I obtained my evidence. Also, we had required no help to set up the equipment during the experiment.
Safety Procedures:
As I have explained in my plan, there were some important safety issues I had to take into account. When recording my results, I had to keep my paper as far away as possible from the solution, so incase the solution was tipped over, the results weren’t lost. Also, to avoid the solution harming any part of my body, I made sure I was protected by wearing goggles, gloves and an apron.
Fair test:
During the experiment, we followed our plan carefully to ensure a fair test. We used a stopwatch so we could precisely calculate how long it took for the reactants to react. Also, there was more than 1 person responsible for confirming when the cross has disappeared; this is to ensure that there’s always a back up incase someone gets distracted.
Explaining the results:
As you can see below, there is a table showing the results of my experiment. I did 6 separate tests and got 3 different times for each temperature. To find out the overall average time for each temperature, we added all 3 results for each temperature and then divide by 3. Then, you convert this to 3 significant figures to be as accurate as possible.
Opinion of plan:
In my opinion, I think that my plan was completed well and that all the factors were controlled as well as possible. Obviously, all our results weren’t as accurate as they could be due to the fact that we were experimenting in a science lab but they were as precise as possible. As we weren’t able to perform the experiment in a perfect environment, we had to work with what we had. If I were to do this experiment again I would use an ICT light sensor that can track the reaction much more accurately than human eyes. I would also use a room which has a constant temperature which is also the same temperature as the experiment, a 1°C room for a 1°C test so that the heat isn’t affected by the room temperature. Lastly, I would use better measuring devices such as burettes to measure things in the experiment.
Table of results:
I followed the method stated in my plan.
Table of average results:
This is the rate of reaction table. I will plot my graphs from this of average time and temperature, and rate and temperature.
Science Coursework: Rates of Reaction
Skill Section A
Introduction:
The procedure was very successful. I saw the sulphur precipitate forming making the solution cloudy. From this I could tell that the reaction was successful. Everything was done according to plan and there were no accidents.
Trends:
According to the graph, we can see that as temperature increases, the time of the reaction decreases; this shows that temperature and time are indirectly proportional, so the graph has proved my prediction. You can see that in the second graph the temperature is directly proportional to the rate of reaction. As temperature increases so does the rate of reaction.
The graph linked back to the Scientific Knowledge and Prediction:
All this happens because of the collision theory: The rate of a reaction simply depends on how often and how hard the reacting particles collide with each other. When increasing temperature, the reactants will vibrate more making it more likely for them to collide and the heat from the energy means that they will have more activation energy, making reactions occur faster as said in my scientific knowledge. The temperature is indirectly proportional to the time of the reaction, and the temperature is directly proportional to the rate of reaction. This explains why the lines of best fit on each graph are going in opposite directions to each other.
Anomalies:
There is 1 anomaly; it was very hard to tell when we should stop timing as it was difficult to judge when the cross was completely covered by precipitate. Also, our reactions are not incredibly accurate, so we may have misreported some results. Ideally, if we were to repeat this experiment without any limits to equipment, I would use an ICT light sensor that can track the reaction much more accurately than human eyes.
Opinion of plan:
My results have proved that my prediction was correct. The higher the temperature the faster the reaction, therefore, the lower the temperature the longer the reaction. If I were to do this experiment again I would use an ICT light sensor that can track the reaction much more accurately than human eyes. I would also use a room which has a constant temperature which is also the same temperature as the experiment, a 1°C room for a 1°C test so that the heat isn’t affected by the room temperature. Lastly, I would use better measuring devices such as burettes to measure things in the experiment.
Science Coursework: Rates of Reaction
Skill Section E
Introduction:
In my evaluation, I shall be expressing how I feel about how the experiment has gone and whether I’m pleased with the outcome or not.
Reliability of results:
I have followed my procedure and have found only the smell putting me off the experiment. The odour of the sulphur dioxide distracted me a bit and may have caused me to make slight mistakes in measurement.
There is 1 anomaly; it was very hard to tell when we should stop timing as it was difficult to judge when the cross was completely covered by precipitate. Also, our reactions are not incredibly accurate, so we may have misreported some results. Ideally, if we were to repeat this experiment without any limits to equipment, I would use an ICT light sensor that can track the reaction much more accurately than human eyes.
Variables that we controlled in the plan:
I have kept all the factors affecting the rate of reactions the same, except for temperature as it is the effect of temperature that I wanted to investigate. I kept the concentration of reactants the same by only using 40cm³ of sodium thiosulphate and 10cm³ of hydrochloric acid. I controlled surface area through using liquids as reactants. Lastly, I controlled the concentration by keeping the molar at 1. I think that I successfully managed to control the variables in this experiment. The variables were controlled so that my results of the experiment were fair and accurate, so that we can build a firmer conclusion on the rates of reaction.
Conclusion:
My prediction was correct. I predicted that the higher the temperature the faster the reaction, which also means, the lower the temperature the longer the reaction (they are indirectly proportional). If I were to do this experiment again I would use an ICT light sensor that can track the reaction much more accurately than human eyes. I would also use a room which has a constant temperature which is also the same temperature as the experiment, a 1°C room for a 1°C test so that the heat isn’t affected by the room temperature. Lastly, I would use better measuring devices such as burettes to measure liquids in the experiment.
Bibliography:
- AQA modular science final exam revision guide
- BBC GCSE Bitesize website
- http://www.headlice.org/lindane/chemicals/hydrochloride.htm