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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 solutio... 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 measure exactly 25.00 cm³ of sodium hydroxide solution with a pipette, follow these steps:
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Use a pipette filler: First, attach a pipette filler to the pipette to draw the sodium hydroxide solution without risk of contamination.
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Wash the pipette: It is essential to rinse the pipette with the sodium hydroxide solution prior to use. This ensures that any water remnants are removed and prevents dilution of the solution during measurement.
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Draw the liquid: Invert the pipette into the sodium hydroxide solution, and gradually release the filler until the solution rises up the neck of the pipette, ensuring that the bottom of the meniscus touches the 25.00 cm³ mark on the pipette. This ensures an accurate measurement.
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Transfer to conical flask: Finally, carefully transfer the solution from the pipette into the conical flask, ensuring that no liquid is left behind in the pipette.
Step 2
Explain why the burette is rinsed with the acid.
Answer
The burette is rinsed with the hydrochloric acid to ensure accuracy in the titration process. This is important for two main reasons:
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To remove water: Rinsing the burette with hydrochloric acid removes any residual water from previous use, which could dilute the acid and lead to an inaccurate concentration during the titration.
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To avoid contamination: Rinsing ensures that the acid inside the burette is the same as that which will be used for the titration. This prevents any possible contamination that could alter the results.