Photo AI
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: Na2S2O... 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 particles as a precipitate during the reaction between sodium thiosulfate and hydrochloric acid. This precipitation occurs when sulfur is produced in the form of solid, which scatters light and causes the appearance of cloudiness in the solution.
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
-
Materials: Gather the following materials:
- Sodium thiosulfate solution (varying concentrations)
- Dilute hydrochloric acid
- Conical flask
- Stopwatch
- Light sensor or a piece of white paper
-
Measurement: Measure a fixed volume of sodium thiosulfate solution and pour it into the conical flask.
-
Timing: Start the stopwatch and then immediately add a fixed volume of dilute hydrochloric acid to the flask.
-
Observations: Observe the reaction and use the light sensor or white paper to determine when the solution becomes cloudy (as the sulfur precipitate forms). Record the time taken for the solution to become cloudy.
-
Repeats: Repeat the experiment with different concentrations of sodium thiosulfate while keeping the volume of hydrochloric acid constant.
-
Control Variables: Ensure to control additional variables such as the total volume of solution and temperature to maintain the reliability of the results.