Transcript Collapsing Can

Reaction of Sodium
and Water
When sodium reacts with water hydrogen gas
and sodium hydroxide are produced
Purpose

To observe the reactivity of a metal
with water
Demonstration

Only a tiny piece of sodium was
used
 since
the reaction is exothermic and
also produces hydrogen gas, too
much heat would cause the
hydrogen to explode
• 2H2 +


O2
2H2O
As the metal reacted, it hissed on a
cushion of hydrogen gas
The sodium hydroxide produced
caused the indicator to turn pink
Concepts
1.
Metals
2.
Bases
3.
Reactions of Metals
1. Metals


Most of the elements of the
Periodic Table are metals
Metals have common properties
 shiny
 maleable
 ductile
 electrically


conductive
Some metals are more reactive
than others
Group IA metals are the most
reactive
2. Bases


A base is a substance that
produces hydroxide ion when
dissolved in water
Common bases are hydroxides of
Group IA and Group IIA metals
LiOH
NaOH
KOH
Mg(OH)2
Ca(OH)2
lithium hydroxide
sodium hydroxide
potassium hydroxide
magnesium hydroxide
calcium hydroxide
3. Reactions of Metals


Metals commonly react with acids
Metals of Group IA react with the
very weak acid, water
Metal + H2O

Metal hydroxide + H2
Reaction of a Group IA metal with
water gives a metal hydroxide and
hydrogen gas
Conclusions




Sodium was more reactive than
other Group II metals
Sodium was so reactive that it
reacted with water
Group IA metals such as sodium
are the most reactive metals
When Group IA metals reacted with
water hydrogen gas was produced
in addition to a metal hydroxide
Comments

This demonstration is an example
of a redox reaction which is a
double replacement reaction
Na + H-OH
NaOH + H2
sodium metal has oxidation number of zero but
ends up as 1+
 hydrogen in water has oxidation number of 1+ but
ends up as zero in hydrogen gas


Magnesium is a Group IIA metal
that will not react with water but will
react with acids