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Define rate of reaction - Leaving Cert Chemistry - Question 3 - 2017
Question 3
Define rate of reaction. In the reaction of sodium thiosulphate solution with hydrochloric acid, according to the following balanced equation, sulfur precipitates a... show full transcript
Worked Solution & Example Answer:Define rate of reaction - Leaving Cert Chemistry - Question 3 - 2017
Step 1
Step 2
Describe a method you could use to determine when the same mass of sulfur had been formed in each run.
Answer
A suitable method would involve observing the endpoint at which a specific mass of sulfur is formed. This can be achieved by:
- Using a light source (such as a piece of paper with a cross drawn on it) placed beneath the reaction flask.
- Mixing the sodium thiosulphate solution with hydrochloric acid and observing the reaction.
- As sulfur precipitates, the solution will become increasingly opaque, causing the cross to disappear from view.
- The time taken for the cross to completely disappear can then be recorded. This time can be used to indicate the formation of sulfur, ensuring uniform conditions in each reaction run.
Step 3
Step 4
Step 5
What can you conclude from your graph?
Answer
The graph depicts a direct relationship between the concentration of sodium thiosulphate and the rate of reaction. As the concentration increases, the rate of reaction also increases, suggesting that they are directly proportional. This implies that higher concentrations result in a quicker formation of sulfur precipitate.
Step 6
Describe how you could use the same reaction to investigate the effect of changing temperature on the reaction rate.
Answer
To investigate the effect of temperature on the reaction rate, you could:
- Keep all other conditions constant while varying the temperature of the reaction mixture.
- Use a water bath to maintain specific temperatures (e.g., 10°C, 20°C, 30°C).
- Measure the time taken for the cross to disappear at each temperature.
- Record the data and plot a graph of temperature versus reaction rate to analyze the results. Baseline control reactions should also be performed for accuracy.