Recently, i received an online enquiry from a Chemistry student asking me about the difference between “Dibasic Acid” and “Diprotic Acid“.This question is not uncommon since you tend to see them during your school’s Chemistry Examinations when you are tested on the topics of Acids, Bases and Preparation of Salts. Unfortunately, a lot of students are confused and when they asked their school Chemistry teachers, no one is able to give them a definite answer or explanation.
Every year, i would also have both my secondary 3 and 4 GCE O-Level Chemistry students asking me this same question in my weekly Chemistry Tuition Classes.
From my knowledge and research, there is no difference between dibasic acid and diprotic acid.
They both mean the same thing which is acid molecules with 2 protons (H atoms) that can be dissociated: e.g. H2SO4 and H2S, as shown below:
H2SO4(aq) –> 2H+(aq) + SO42-(aq)
H2S (aq) –> 2H+(aq) + S2-(aq)
Since two protons are released, both H2SO4 and H2S are diprotic (= forming two protons).
The two anions (SO42- and S2-) are both bases (this is covered under Bronsted-Lowry Acids & Bases in GCE A-Level Chemistryi.e. Advanced Chemistry and equivalent syllabus. Students taking the GCE O-Level syllabus do not need to know these concepts).
So both H2SO4 and H2S is dibasic (= forming two bases).
However, it seems like diprotic is a more modern Chemistry term used for dibasic these days.
Note:
1) If you need to learn Bronsted-Lowry Acids & Bases, you can go to my A-Level H2 Chemistry blog (for JC1, JC2 and IB students) to learn more about Advanced Chemistry. Go to: http://www.ALevelH2Chemistry.com
2) If you are new to the concepts on Acids, do check out my blog post on 22 August 2008 where i shared on the definition of “Basicity” with common examples.
Hope you find the above useful. Do let me know your thoughts on it.
To Your Chemistry Success,
Sean Chua
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