What is a base?

 Hello everyone, I am glad to welcome you into the month of July! For most of this month, our discussion would center around the concept of BASES. Remember that I have mentioned bases on time or another in our discussion about acids. For instance, I said that acids form salts when they react with bases(refer to the lesson on properties of acids). I reserved the discussion about bases for a latter time because I believe that our lessons ought to be sequential and concepts should be discussed in a logical manner so that the learner can make the most sense out of the material.


What exactly are bases? Again we have quite some definitions just as we had for acids. We majored on three definitions of acids and we would also major on three definitions of bases. We are going to start with the most elementary definition of bases today and then take the matter up from there.


The most basic definition of a base was given by Arrhenius. According to this definition, a base is a substance that produces hydroxyl or hydroxide ions (OH^-) in aqueous solution. In order words, for a substance to qualify to be called a base from the Arrhenius perspective, the following conditions must be met;

1) The substance must contain the hydroxyl ion

2) The substance must dissolve in water to release the hydroxyl ion (must form an aqueous solution containing hydroxyl ion).

Let us see a few examples of compounds that qualify as bases in this sense;

1) Ca(OH)2(s) --->Ca^2+(aq) + 2OH^-(aq)

2) NaOH(s) ----> Na^+(aq) + OH^-(aq)

3) Al(OH)3(s) --> Al^3+(aq) + 3OH^-(aq)

What are the common denominators in all the reactions shown above? Let me know in the comments section.


Just like we observed when we were looking at acids, the definition of Arrhenius is limited to;

1) Substances that contain hydroxyl ions

2) Substances that dissolve in water


What if a compound hasn’t any of these characteristics? Then the substance can not possibly be a base in the Arrhenius sense of it. Is this an absolutely correct view of bases? Well, you would need to follow our page closely throughout the month to find out about that!


Once again, happy new month!


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