GCSE Edexcel Chemistry Titrations: Step J: Pour the potassium hydro

Question

Step J: Pour the potassium hydroxide solution into a conical flask and add a few drops of indicator to this solution.

Step K: Fill a burette with the dilute hydrochloric acid and record the initial reading from the burette.

Step L: Use a measuring cylinder to obtain 25 cm³ of potassium hydroxide solution.

Step M: Take a final reading from the burette and calculate the volume of the dilute hydrochloric acid reacted.

Step N: Run the dilute hydrochloric acid from the burette into the conical flask until the indicator changes colour.

(i) Write the steps in the correct order.

(ii) Suggest an alternative piece of apparatus that could be used in step L to obtain exactly 25.0 cm³ of potassium hydroxide solution.

(b) A student was then asked to produce a pure sample of solid potassium chloride.

After finding the volume of acid reacted in step M, the student added this volume of acid to a fresh 25.0 cm³ sample of the potassium hydroxide solution. This mixture was then evaporated.

(iii) Explain why this new mixture was evaporated rather than the original mixture from the titration to produce a pure sample of solid potassium chloride.

(ii) After evaporation, the mass of the potassium chloride was determined. The theoretical yield of the experiment was 0.70 g. The actual yield was 0.84 g.

Calculate a percentage yield of this experiment.

(iii) Suggest a reason why the actual yield was greater than the theoretical yield.

Calculate the atom economy for the production of potassium chloride from potassium hydroxide and hydrochloric acid.

(relationship formula mass: KOH = 56.0, HCl = 36.5, KCl = 74.5, H₂O = 18.0)

Give your answer to one decimal place.

Step J: Pour the potassium hydroxide solution into a conical flask and add a few drops of indicator to this solution - Edexcel - GCSE Chemistry - Question 4 - 2020 - Paper 1

Worked Solution & Example Answer:Step J: Pour the potassium hydroxide solution into a conical flask and add a few drops of indicator to this solution - Edexcel - GCSE Chemistry - Question 4 - 2020 - Paper 1

Suggest an alternative piece of apparatus that could be used in step L to obtain exactly 25.0 cm³ of potassium hydroxide solution.

Explain why this new mixture was evaporated rather than the original mixture from the titration to produce a pure sample of solid potassium chloride.

Calculate a percentage yield of this experiment.

Suggest a reason why the actual yield was greater than the theoretical yield.

Calculate the atom economy for the production of potassium chloride from potassium hydroxide and hydrochloric acid.

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