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Expt:Extracting metals with charcoal

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Contents

Introduction

In each of the two experiments, illustrating the idea of competition between metals and carbon, students heat a metal oxide with powdered charcoal. If the carbon is more reactive than the metal it will remove the oxygen from the metal oxide and leave traces of the metal in the reaction vessel. The first experiment uses lead(II) oxide; the second modifies the technique slightly and uses copper(II) oxide.

Apparatus and chemicals

  • Eye protection

Each student or pair of students will require:

  • Small, hard glass test-tubes (ignition) tubes (3) (see note 1)
  • Test-tube holder
  • Test-tube rack
  • Spatula
  • Plastic weighing dish (boat)
  • Heat resistant mat
  • Access to:
  • Lead(II) oxide (Toxic, Dangerous for the environment), about 1 g (see note 2)
  • Powdered charcoal, about 2 g
  • Copper(II) oxide (Harmful, Dangerous for the environment), about 1 g

Technical notes

Lead(II) oxide (Toxic, Dangerous for the environment) Refer to CLEAPSS® Hazcard 56

Copper(II) oxide (Harmful, Dangerous for the environment) Refer to CLEAPSS® Hazcard 26

  1. Test-tubes made of heat resistant borosilicate glass (Pyrex or similar) must be used. Testtubes with a capacity of about 10 cm3 are ideal. It is important that the test-tubes are dry. Heating lead and its compounds strongly in glass often results in the lead compounds fusing into the glass, rendering the test-tube impossible to re-use. If this is an issue, old, but unstained test-tubes can be used and discarded after this use.
  2. The three solids may be dispensed in separate, labelled, plastic weighing dishes. It is wise to withhold the copper(II) oxide until it is required to avoid the students confusing it with the charcoal.

Procedure

Health & Safety

Wear eye protection throughout. The room should be well ventilated.

Procedure

Experiment 1

A. Transfer one small spatula measure of lead(II) oxide to the empty weighing dish.

B. Add one spatula measure of charcoal powder.

C. Mix the two powders together using a spatula.

D. Transfer the mixture into a hard-glass test tube and strongly heat this mixture for five minutes in a Bunsen flame.

E. Allow the test-tube to cool in its holder on a heat resistant mat.

F. Tip the cooled mixture out onto the heat resistant mat.

Experiment 2

A. Transfer one spatula measure of copper(II) oxide to a hard glass test-tube.

B. Carefully add one spatula of charcoal powder on top of the copper oxide without any mixing.

C. Strongly heat these two layers for five minutes in a Bunsen flame.

D. Allow to cool and then look closely at where the powders meet in the test-tube.

apparatus for extracting metals with charcoal experiment

Reference

This experiment has been adapted from Practical Chemistry: http://practicalchemistry.org/experiments/extracting-metals-with-charcoal,305,EX.html

Useful Resource

A number of other experiments on the website also illustrate the competition principle.

Examples include:

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