1. When sodium reacts with water hydrogen gas and sodium hydroxide are produced Reaction of Sodium and Water

2. Purpose n To observe the reactivity of a metal with water

3. Demonstration n Only a tiny piece of sodium was used F since the reaction is exothermic and also produces hydrogen gas, too much heat would cause the hydrogen to explode 2H 2 + O 2 2H 2 O n As the metal reacted, it hissed on a cushion of hydrogen gas n The sodium hydroxide produced caused the indicator to turn pink

4. Concepts 1.Metals 2.Bases 3.Reactions of Metals

5. 1.Metals n Most of the elements of the Periodic Table are metals n Metals have common properties u shiny u maleable u ductile u electrically conductive n Some metals are more reactive than others n Group IA metals are the most reactive

6. 2.Bases n A base is a substance that produces hydroxide ion when dissolved in water n Common bases are hydroxides of Group IA and Group IIA metals LiOHlithium hydroxide NaOHsodium hydroxide KOHpotassium hydroxide Mg(OH) 2 magnesium hydroxide Ca(OH) 2 calcium hydroxide

7. 3.Reactions of Metals n Metals commonly react with acids n Metals of Group IA react with the very weak acid, water Metal + H 2 OMetal hydroxide + H 2 n Reaction of a Group IA metal with water gives a metal hydroxide and hydrogen gas

8. Conclusions n Sodium was more reactive than other Group II metals n Sodium was so reactive that it reacted with water n Group IA metals such as sodium are the most reactive metals n When Group IA metals reacted with water hydrogen gas was produced in addition to a metal hydroxide

9. Comments n This demonstration is an example of a redox reaction which is a double replacement reaction Na + H-OH NaOH + H 2 F sodium metal has oxidation number of zero but ends up as 1+ F hydrogen in water has oxidation number of 1+ but ends up as zero in hydrogen gas n Magnesium is a Group IIA metal that will not react with water but will react with acids