Question

38
Different metals were tested using the apparatus shown.
Metal 1-
Metal 2
11
Which pair of metals would produce the largest voltage?
Copper and silver
Magnesium and silver
C
Magnesium and zing
Zinc and copper
12​

Answer 1

Answer:

The experiment is done first on a smaller scale using test tubes (lesson 1 below), with no attempt to recover the salts formed. This establishes that hydrogen production is a characteristic property of the reaction of metals and acids. It can then be done on a larger scale (lesson 2 below), and the salts formed can be recovered by crystallisation.

Lesson 1 is a series of test tube experiments in which each working group establishes as a common feature that hydrogen is given off as metals react with an acid – if the metal reacts at all. This should take around 40 minutes, and most classes should be able to do this version. Each working group needs a small selection of metals and acids to test.

The range of metals and acids tested can be extended to a teacher demonstration in the concluding part of this lesson.

Lesson 2, in which the salt formed is recovered by crystallisation, takes longer, and the class needs to be reliable enough in behaviour and manipulative skills to cope with the hazards involved in heating acidic solutions in beakers on tripods.

The time taken for the reaction depends on the particle size of the metal used. Using small granules helps to reduce the time taken.