Learning objectives

That acids react with some metals to produce new substances, including hydrogen.
Learning outcomes

Conclude that when hydrogen was made a chemical reaction had taken place.
Context
During an earlier part of the lesson pupils will have carried out a practical to establish that bubbles of gas and heat can be observed when some metal react with acids.
Lesson Outline
Plenary:
1. Write word equation board using contributions from pupils
Metal + acid hydrogen
2. Invite pupils to come up to add particle pictures for metal (solid) and acid
(liquid). Provide the opportunity for pupils to use different colour pens for the two different materials.
3. Invite pupils to come up to draw the hydrogen that is made. The should readily show that it is a gas by drawing large spaces between the particles but an interesting discussion can arise regarding the colour that is chosen for the hydrogen particles. Some will suggest using both colours used for metal and acid particles but others will insist a new colour should be used, as hydrogen is not the same as metal or acid. There is an opportunity to include ideas about heat evolved or colour changes that can result from this “change in identity” of particles and to discuss the “disappearance” of magnesium when it reacts with acid.