In the last post, we have covered Chemical Definitions of ACIDs. Today we are going to cover on the “Basicity of ACIDs” – this part is where lots of students have misconception in their schools.
Do note that “BASICITY of ACIDs” is associated with the acids itself, and not on BASES. Many students always argued that Basicity comes directly from the word BASE itself and should only be associated with BASE as “BASICITY of BASEs”. I want to highlight over here that this is incorrect! Best way to persuade you would be checking out the Chemical Definition of “BASICITY”.
Definition of Basicity of An Acid:
Basicity of an acid refers to the number of replaceable hydrogen atoms in one molecule of the acid
Lets look closer on the 3 common types of Basicity of an acid.
Monobasic
Definition: 1 molecule produce 1 H+ ion upon dissociation
Example: HCl, HNO3
Dissociation Equation: HCl(aq) –> H+(aq) + Cl-(aq)
Dibasic
Definition: 1 molecule produce 2 H+ ion upon dissociation
Example: H2SO4
Dissociation Equation: Figure it out yourself!!
Tribasic
Definition: 1 molecule produce 3 H+ ion upon dissociation
Example: H3PO4
Dissociation Equation: H3PO4(aq) –> 3H+(aq) + PO4 3-(aq)
Learnt something from the above already? Good! Now, let’s try out an exam-based questions that are associated with it.
Quick Check 1:
Sulphuric acid is a dibasic acid because:
A. each molecule contain 2 hydroxide ions
B. each molecule can produce 2 hydrogen ions
C. one mole of the acid contains two atoms of hydrogen that can be replaced by a metal
D. sulphuric acid can only be neutralized by 2 bases
E. sulphuric acid has the usual properties of an acid, but is also a dehydrating agent
PS: Do leave your suggested answers in the “Comments Section” directly below this post.
PPS: This post belongs to a series of blogposts that is associated with Secrets of “Acids, Bases & Salts and Qualitative Analysis revelaed”
answer is B
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Well Done Adithya.
Keep up that good work.
Cheers
Sean
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why isnt the answer C? True, the answer is B, but what is the difference between B and C?
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sean Reply:
April 24th, 2009 at 3:09 pm
Thanks Joe for the participation.
The question is asking you about the definition of “Dibasic Acid” which is the answer for (B).
You need to know this definition well for GCE O Levels and ICGSE syllabus.
Hope this information clarify your doubts.
Let me know if you need further clarification.
To Your Academic Success in Chemistry.
Sean Chua
Master Trainer & Author
WINNERS Education Group
“Experience Learning with A Difference”
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HI!
i have a question.when determining the basicity of the acid,why we have to divide number of moles of a metal hydroxide by no of moles of the acid??i dont understand.hope you can help me .thank you!
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sir how to find the basicity of an acid in order to find equivalent weight of acids ?
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sean Reply:
May 10th, 2011 at 11:06 am
Hi Anwesha,
Try this out: http://easycalculation.com/chemistry/weightofacid.php
Hope this helps. Enjoy learning Chemistry.
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sir
why is it called basicity of an acid not acidity?
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sean Reply:
August 19th, 2011 at 1:34 am
Because it refers to how many moles of the acid that is required to react with the base.
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The ans is B
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sir how do we identify basicity of an acid in an equation. Thx
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