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Edexcel A-Level Chemistry AS 3 P6 Evaluating an Experimental Method Questions

Practise Edexcel IAL Chemistry 3.P6 by explaining apparatus and reagent choices, why each procedural step is needed and how changes improve accuracy and reliability.

Syllabus
First assessment 2019
Course
Chemistry YCH11
Level
AS

Exam points

  • explain apparatus and reagent choices that control retention, support, gas flow and endpoint reliability
  • Use heating to constant mass as evidence that reaction or water removal is complete.
  • Suggest a method improvement and state how it changes loss, completion or measurement bias.

Edexcel A-Level Chemistry AS 3 P6 Evaluating an Experimental Method Questions question 1

[Maximum number: 2]

A class of students carried out experiments to determine the enthalpy change for the reaction of magnesium metal with hydrochloric acid. The following method was used. Step1 A 1.00 m length of magnesium ribbon was cleaned using sandpaper, weighed and cut into 10 cm lengths. Step 250 cm3250 \mathrm{~cm}^{3} of dilute hydrochloric acid (an excess) was placed into a polystyrene cup and the temperature measured. Step 3 A 10 cm length of magnesium ribbon was added to the hydrochloric acid. The solution was stirred gently and the maximum temperature recorded.

Mg+2HCl→MgCl2+H2\mathrm{Mg}+2 \mathrm{HCl} \rightarrow \mathrm{MgCl}_{2}+\mathrm{H}_{2}

Results

Table for Question Edexcel A-Level Chemistry AS 3 P6 Evaluating an Experimental Method Questions question 1 — Edexcel A-Level Chemistry AS

Explain why the magnesium ribbon was cleaned with sandpaper before being weighed.

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