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Sodium thiosulfate solution reacts with dilute hydrochloric acid - AQA - GCSE Chemistry - Question 5 - 2018 - Paper 2
Question 5
Sodium thiosulfate solution reacts with dilute hydrochloric acid. The solution becomes cloudy as the reaction takes place. The equation for the reaction is: Na2S2... show full transcript
Worked Solution & Example Answer:Sodium thiosulfate solution reacts with dilute hydrochloric acid - AQA - GCSE Chemistry - Question 5 - 2018 - Paper 2
Step 1
Explain why the solution becomes cloudy.
Answer
The solution becomes cloudy due to the formation of sulfur precipitate during the reaction between sodium thiosulfate and hydrochloric acid. As sulfur forms, it appears as a solid that suspends in the solution, causing the mixture to appear opaque or cloudy.
Step 2
Plan an investigation to show how the concentration of the sodium thiosulfate solution affects the rate of the reaction with dilute hydrochloric acid.
Answer
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Measure the indicated volume of sodium thiosulfate solution and dilute hydrochloric acid.
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Prepare a conical flask by adding the sodium thiosulfate solution.
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Add a specific volume of hydrochloric acid to the conical flask quickly.
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Start a timer immediately when the acid is added.
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Swirl the flask to mix the solutions thoroughly.
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Observe and record the time taken for a cross placed underneath the flask to become no longer visible due to the cloudiness of the solution.
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Repeat the experiment for varying concentrations of sodium thiosulfate to compare the times recorded.
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Control variables: Use the same volume and concentration of hydrochloric acid throughout the experiments. Ensure the same cross marking and maintain the same volume of sodium thiosulfate for each trial.