When do metals react

When these elements react, an electron has to be transferred from one element to the other. We can decide which element should lose an electron by comparing the first ionization energy for potassium Click here to check your answer to Practice Problem 1.

Salts Oxidation and Reduction. Practice Problem 1: Write a balanced equation for the following reaction. 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. Apparatus for recovering salt formed by the reaction of zinc and sulfuric acid.

Use the student handout available with this resource and get the students to answer each question after observing the reaction. Safety is particularly relevant to younger students. Be aware of the problems associated with heating beakers or evaporating dishes on tripods, and with lifting such hot containers off a tripod after heating. Students should not be seated on laboratory stools while carrying out these operations.

Using tongs of suitable size is a good way of lifting hot containers but some schools may not have these. If there is any doubt about the safety of this step, the teacher should first lift each beaker down onto the heatproof mat, using a thick cloth or wearing suitable thermal protection gloves, before the students add the zinc pieces.

The same applies to moving the evaporating basin before pouring its contents into the crystallising dish. The procedure for safely testing the evolved hydrogen gas in the test tube reactions needs to be demonstrated at a suitable point in lesson 1.

A loosely inserted cork allows sufficient build-up of gas in a slow reaction to enable a successful test. This pair of experiments forms an important stage for younger students in developing an understanding of what an acid is.

They need to understand how to generalise from sufficient examples, and to see the limits to that generalisation in metals that do not react. It may help to develop this discussion in the concluding stages of lesson 1 by additional demonstrations of other metals and acids.

By the end of the lesson, students should be able readily to draw the conclusion:. Describe and explain the observations when a small piece of lithium is placed on the surface of a big container of water. A few drops of universal indicator have been added to the water. There is fizzing as the lithium reacts with the water to produce hydrogen gas. The colour of the universal indicator changes from green to purple as an alkaline solution of lithium hydroxide is produced.

When a metal reacts with a dilute acid , a salt and hydrogen are formed. For example, magnesium reacts rapidly with dilute hydrochloric acid:. Sodium is highly active and is able to displace hydrogen from water:.

Less active metals like iron or zinc cannot displace hydrogen from water but do readily react with acids:. The boundary between the metals that react with water and those that don't is harder to spot. For example, calcium is quite reactive with water, whereas magnesium does not react with cold water but does displace hydrogen from steam. A more sophisticated calculation involving electrode potentials is required to make accurate predictions in this area.