1)Why is this answer C? Citric acid is a triprotic acid with Ka1=7.4×104 . Which
ID: 529546 • Letter: 1
Question
1)Why is this answer C?
Citric acid is a triprotic acid with Ka1=7.4×104 . Which of the following is the most likely value for Ka2? A. Very large B. 7.4×104 C. 1.7×105 D. 6.0×102 E. It is impossible to determine between these values.
2) Why is this answer to this problem below d?????
Which equilibrium explains why a dissolving Fe 3+ in water results in an acidic solution? A. Fe 3+ (aq) + H2O() HFe 3+ (aq) + OH (aq) B. Fe(H2O)6 3+ (aq) Fe(OH)3(s) + 3H3O+ (aq) C. Fe 3+ (aq) + 3H2O() Fe2O3(aq) + H3O+ (aq) D. Fe(H2O)6 3+ (aq) + H2O() Fe(H2O)5(OH) 2+ (s) + H3O+ (aq) E. None of the above
3) Why isn't Na2CO3 included in the solution (equilibrium equation) and ICE table?? Please help I have an exam and am very confused on this one the most
What is the concentration of magnesium when MgCO3 (Ksp=6.82×106 ) is added to a 0.15 M Na2CO3 solution?
Explanation / Answer
Answer :
For tri protic acid like Citric acid (say H3A) there are 3 ionizable protons and Ka value corresponding to each dissociation say ka1, Ka2, Ka3 going to be different.
In polyprotic weak acid case it follows the general trend as Ka1 > Ka2 > Ka3 ..... so on.
At the first ionisation, the species which ionises is the absolute acid i.e.H3A here.
But on succeeding ionisations it is the conjugate base (i.e. H2A- here for Ka2).
The conjugate base is less stable than acid itself i.e. H2A- is less stable than H3A and hence it resist further ionisation to a greater extent than acid itself.
It means ionisation tendency of H2A- is less than H3A and hence the observer trend is Ka1 > Ka2.
I.e. Ka2 second ionisation constant value like to be smaller than that of Ka1.
Which is in the option (c) C. 1.7×105.
Hence Answer Option (c).
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