Chemical Reactions - Evidence D. Crowley, 2007

Chemical Reactions - Evidence To identify evidence for a chemical reaction Sunday, August 16, 2015Sunday, August 16, 2015Sunday, August 16, 2015Sunday, August 16, 2015

Which metal? Using your sheet, cut out the five descriptions of metals Then stick them in your book, from the most reactive (sodium) to the least reactive (gold)

Previous reactions In this unit, you have seen the following reactions: - metal + oxygen → metal oxide metal + water → metal hydroxide + hydrogen metal + acid → salt + hydrogen

Chemical reaction Can you think of at least three things which prove a chemical reaction has taken place? New compounds form – with new properties New compounds form – with new properties There may be a colour change There may be a colour change Heat may be released Heat may be released A gas may be given off A gas may be given off The pH may have changed (compound formed is acidic / alkaline) The pH may have changed (compound formed is acidic / alkaline)

Demo Look at the demo of some compounds being formed You need to observe what is happening: - –Has a gas been given off? –Is there a colour change –Is there a pH change –Is there a temperature variation?

Demo + Worksheet Watch the repeated demo This time, fill in your sheet ticking if a gas was given off; there was a colour change; there was a pH change; or if there was a variation in temperature…

Anagrams Look at the following, jumbled up words See if you can rearrange them: - e.g. talme become metal nno-melatouncdpmodplacmenteisnedghroyTalsractiveeacdi non-metalcompounddisplacementhydrogensaltreactiveacid→→→→→→→