This week in triple science we were carrying out our planned experiments . We were given all the resources we needed and then it was up to us to complete the practical by using the method we had written. My hypothesis was the higher concentration of acid the faster the rate of reaction.
Some of us found that our experiments didn’t quite work and needed to be changed slightly in order to answer our hypothesis. Most of us repeated our experiments 3 times to make sure our results were reproducible and reliable. This was important because it helped us to see if we had any anomalies in our results and if we did we could see where something had gone slightly wrong.
It was quite challenging doing the experiment without being told how to do it first and without having help planning and carrying it out. I thought the practicals were a good way to help build confidence and be more independent. Also, we could get help from each other, for example if you weren’t sure what to do next instead of asking a teacher you could ask another student to help you.
In my experiment I tested the rate of reaction when adding different concentrations of hydrochloric acid to sodium thiosulfate. My concentrations of hydrochloric acid were 0.5m, 1m and 2m. This was a picture before the reaction of sodium thiosulfate and hydrochloric acid took place and a picture of it after the reaction.

I knew the reaction was finished because the clear liquids became a white colour and I could not see the cross on the paper underneath the glass beaker. The experiment went that colour because a sulphur precipitate was produced.

This was another student’s experiment measuring the effects of different concentrations on the amount of gas produced.

In Fridays lesson, the class took part in a quiz. We were separated into 4 groups, 10H1 Girls, 10H1 boys, 10H2 girls and 10H2 boys. In our groups we had to choose a runner. The runner’s job was to get a question from the middle table where our teacher was sitting and bring it back to our group. We answered the question and the runner took it back to the teacher to check. If it was correct we took another question to answer, if it was incorrect we had one more go before we lost the point. At the end of the game the scores were counted up to see which group had won. 10H1 AND 10H2 girls were joint first place followed by 10H1 boys then 10H2 boys. The quiz was a fun way for us to recap what we had learnt this term.

Exam question: Do your results support the hypothesis you investigated? Use examples from your results in your answer
Answer: Yes my results do support my hypothesis. I predicted that the higher the concentration of acid the faster the rate of reaction. My highest concentration was 2M and had the fastest time which was 24. My lowest concentration was 0.5M and took the longest time of 27 seconds.
Exam question: was your experiment reliable?
Answer: yes, my experiment was reliable because I repeated the experiment three times and got similar answers. There were no anomaly’s and when comparing results with another student, we found our results were similar. This means the experiment was reliable and reproducible.

The theme of this week was the idea of being independent and being able to create an experiment to find out how certain factors affect the rate of reaction, without any help.

At the beginning of the week, we were given a booklet; within this booklet, we had to find two sources, briefly evaluate them, write a hypothesis, explain the hypothesis, write a brief method, complete a risk assessment and draw out the table for our results to go in. We started by choosing the factor we were going to test. For example, the choice were: Temperature, concentration, surface area or catalysts. I chose to do surface area. After this, we used iPads to research two different website which were appropriate to our chosen factor; we had to list what was good and bad about them. Furthermore, we used the information from our research to complete the booklet.

After we had completed the booklet, we were given another booklet to write everything up in detail and use it as preparation for our experiment. We had to explain the hypothesis, evaluate the sources, write a clear method and equipment list (describing the uses of the equipment) and then write a risk assessment and draw the exact table we would be using. All of this ensure that our experiments will run smoothly and the method needed to be clear so that anyone could look at it and repeat the same experiment.

To conclude, the part which I found the most interesting this week is that we have been given responsibility for our work and that we could choose the experiment and how we are going to investigate how our chosen factor affects the rate of reaction. Next week, we will be carrying out the experiment and finding out whether we have proved or disproved our hypothesis. One thing that I could say that I have found difficult is not being able to ask for help as I am someone who needs confidence in myself in order to be able to do my work without assistance.

Exam Questions

1) State 2 factors which affect the rate of a reaction. (2 marks)

2) Describe the effect of concentration on rate of reaction. (1 mark)

3) Explain why a reaction between concentrated acid and magnesium is faster than one with diluted acid. (3 marks)

Answers

1) 1 mark per factor.
Possible answers:
– Catalysts
– Surface area
– Concentration
– Temperature

2) 1 mark= As you increase the concentration, the rate of a reaction increases.

3) 1 mark = Concentration is increased
1 mark = Therefore there are more particles and more frequent collisions.
1 mark = Reaction will happen faster.

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