Question

2.) How can you prove that sodium hydroxide (NaOH) is a base?​

Answer 1

WHEN WE PLACE LITMUS PAPER IN SODIUM HYDROXIDE AND THE LITMUS PAPER TURNS INTO BLUE COLOUR THEN IT IS A BASE... AND IF IT TURNS INTO RED SODIUM HYDROXIDE WILL BE ACIDIC... WE CAN DO A REACTION WITH SODIUM HYDROXIDE WHICH WILL PROCEED ONLY IF IT THE pH IS VERY HIGH.. THIS WILL PROVE IT IS A HIGH pH BASE..

Answer 2

Answer:

You can do a reaction with sodium hydroxide which will proceed only if the pH is very high, proving sodium hydroxide is a high pH base.

This is how:

Al2O3 + 2 NaOH --> 2Na+ + 2[Al(OH)4]-

The species, [Al(OH)4]- is the tetrahydroxoaluminate complex ion. It only appears at high pH. At low pH you cannot get it to form and thus, you will get no further reaction because you cannot dissolve the aluminum oxide coating on the metal. Fortunately, we are using sodium hydroxide and low pH is not even a remote possibility!

Now that you have pure aluminum metal, you can react that with more sodium hydroxide:

2 Al + 2 NaOH + 6 H2O → 2 Na+ + 2[Al(OH)4]- + 3 H2 (gas)

So there you have it. Caution, the reaction liberates a lot of heat, and hydrogen gas, and it usually ignites.

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