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Wednesday, 7 March 2007
SAT Question of the Day
Which is the correct order of decreasing acidity for the aqueous solution of the following acids:
The right answer is "A". The acidity of the acids is different in aqueous solution from that in the gas phase. In the gas phase the correct order would be "B" -because of the atom's electronegativity (F>Cl>Br..).In water, however, the electrostatic and Columbian attractions play a greater role, therefore Iodine because of its greater volume would tend to stay dissociated, while Fluorine because of its small volume and negative charge would tend to attract a proton from water to form HF. The literature values for the pKa of the aqueous solution of the acids: pKa HI = -10, pKa HBr = -9, pKa HCl=-7, pKa HF= 3.2 This values also support the above mentioned theory.
The F is the ellement with the biggest electronegativity so the atraction between H and F is very high, but the I has the lowest electronegativity, it can donate the H. The Broensted Theory of acid and base says that an ACID: Is a substance which can donate proton
11 comments:
isnt it B ?
I think it's B
It seems like B
A or D. leaning on A
The right answer is "A".
The acidity of the acids is different in aqueous solution from that in the gas phase. In the gas phase the correct order would be "B" -because of the atom's electronegativity (F>Cl>Br..).In water, however, the electrostatic and Columbian attractions play a greater role, therefore Iodine because of its greater volume would tend to stay dissociated, while Fluorine because of its small volume and negative charge would tend to attract a proton from water to form HF.
The literature values for the pKa of the aqueous solution of the acids: pKa HI = -10, pKa HBr = -9, pKa HCl=-7, pKa HF= 3.2
This values also support the above mentioned theory.
wats pKa?
The F is the ellement with the biggest electronegativity so the atraction between H and F is very high, but the I has the lowest electronegativity, it can donate the H. The Broensted Theory of acid and base says that an ACID: Is a substance which can donate proton
is get that but wats pKa?
pKa is the negative logarithm of the acidity constant
pKa = -lgKa
Ka is the acidity constant, and for an acid is defined as:
HA+ H2O <=> A- + H3O+
Ka = [A-][H3O+]/[HA]
ha, I will try out my thought, your post get me some good ideas, it's truly awesome, thanks.
- Murk
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