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A titration of sodium hydroxide solution with hydrochloric acid can be carried out as follows: 1 - Edexcel - GCSE Chemistry - Question 2 - 2018 - Paper 1
Question 2
A titration of sodium hydroxide solution with hydrochloric acid can be carried out as follows: 1. a pipette is used to measure 25.00 cm³ of sodium hydroxide solution... show full transcript
Worked Solution & Example Answer:A titration of sodium hydroxide solution with hydrochloric acid can be carried out as follows: 1 - Edexcel - GCSE Chemistry - Question 2 - 2018 - Paper 1
Step 1
Describe how the pipette should be used to measure exactly 25.00 cm³ of sodium hydroxide solution into the conical flask.
Answer
To accurately measure 25.00 cm³ of sodium hydroxide solution using a pipette, the following steps should be taken:
- Use a pipette filler: Always employ a pipette filler to draw up the sodium hydroxide solution. This ensures safety and prevents contamination.
- Wash the pipette: Prior to measuring, the pipette should be rinsed with the sodium hydroxide solution to avoid contamination and ensure an accurate measurement.
- Draw the liquid correctly: Draw the solution into the pipette until the bottom of the meniscus touches the 25.00 cm³ mark. Ensure that you are viewing the measurement at eye level to avoid parallax error, and then release the solution into the conical flask.
Step 2
Explain why the burette is rinsed with the acid.
Answer
Rinsing the burette with hydrochloric acid is essential for the following reasons:
- Avoiding contamination: Rinsing the burette with the acid removes any water or other contaminants that may remain from previous experiments. This ensures that the acid solution is not diluted, which would affect the results of the titration.
- Maintaining concentration: By rinsing the burette with the acid, the original concentration of the hydrochloric acid is preserved. If the burette were filled without rinsing, the residual water could dilute the acid, leading to an inaccurate titration result.