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Sodium thiosulfate solution, Na2S2O3, reacts with dilute hydrochloric acid - Edexcel - GCSE Chemistry - Question 6 - 2020 - Paper 1
Question 6
Sodium thiosulfate solution, Na2S2O3, reacts with dilute hydrochloric acid. Na2S2O3(aq) + 2HCl(aq) → 2NaCl(aq) + H2O(l) + SO2(g) + S(s) (i) When dilute hydrochlori... show full transcript
Worked Solution & Example Answer:Sodium thiosulfate solution, Na2S2O3, reacts with dilute hydrochloric acid - Edexcel - GCSE Chemistry - Question 6 - 2020 - Paper 1
Step 1
Explain why the mixture turns cloudy.
Answer
The mixture turns cloudy due to the formation of sulfur precipitate. When hydrochloric acid reacts with sodium thiosulfate, sulfur dioxide and solid sulfur are produced as products. The solid sulfur particles scatter light, making the solution appear cloudy.
Step 2
Describe how the rate at which the mixture goes cloudy can be measured.
Answer
The rate at which the mixture goes cloudy can be measured using a stopwatch and a piece of paper with a marked 'X' underneath the reaction vessel. As the reaction proceeds and the mixture becomes cloudy, the time taken for the 'X' to no longer be visible is recorded. This time can be used to determine the rate of reaction; shorter times indicate faster reaction rates.