# How do you determine the order of least to most basic in the following

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HCO3-, F-, I- and LiH.

I do not know how to approach it.

I could guess, but I have no method of finding this.

Edited by CrazCo
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Remember that the conjugate base of a weak acid is a strong base. Inversely, the conjugate base of a strong acid is a weak base.

-One of the bases you listed is the conjugate base of a very strong acid...that means that species is a very weak base.

-The conjugate acid of [ce]HCO_{3}^-^[/ce] is [ce]H_{2}CO_{3}[/ce] is that a strong acid, a weak acid, or a "stronger-weak" acid?

-One of the species you listed yields a quite basic metal hydroxide in aqueous solution. Think about the Arrhenius definition of a base.

-You could always look up a table of $pK_{a}$ values if you know what those are.

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Remember that the conjugate base of a weak acid is a strong base. Inversely, the conjugate base of a strong acid is a weak base.

-One of the bases you listed is the conjugate base of a very strong acid...that means that species is a very weak base.

-The conjugate acid of [ce]HCO_{3}^-^[/ce] is [ce]H_{2}CO_{3}[/ce] is that a strong acid, a weak acid, or a "stronger-weak" acid?

-One of the species you listed yields a quite basic metal hydroxide in aqueous solution. Think about the Arrhenius definition of a base.

-You could always look up a table of $pK_{a}$ values if you know what those are.

Thanks!

So hydrofluoric acid is a weak acid, therefore F- is a strong base!

Hydroiodic is a strong acid, therefore I- is a weak base!

Carbonic acid is a weak acid, therefore HCO3- is a strong base!

I am not sure about LiH, but I don't know how to determine whether HF is weaker or stronger than HCO3-

Edited by CrazCo
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Thanks!

So hydrofluoric acid is a weak acid, therefore F- is a strong base!

Hydroiodic is a strong acid, therefore I- is a weak base!

Carbonic acid is a weak acid, therefore HCO3- is a strong base!

Yeah you've got it. But be careful with the terms strong and weak, something can only be truly strong if it dissociates into its constituent ions 100% in aqueous solution. So [ce]HCO_{3}^{-}[/ce] is technically not a strong base but it is a "stronger-weak base", same goes for [ce]F^{-}[/ce].

I am not sure about LiH, but I don't know how to determine whether HF is weaker or stronger than HCO3-

Here's a hint: [ce]HF[/ce] is one of the strongest of the common weak acids.

Edited by mississippichem
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Yeah you've got it. But be careful with the terms strong and weak, something can only be truly strong if it dissociates into its constituent ions 100% in aqueous solution. So [ce]HCO_{3}^{-}[/ce] is technically not a strong base but it is a "stronger-weak base", same goes for [ce]F^{-}[/ce].

Here's a hint: [ce]HF[/ce] is one of the strongest of the common weak acids.

Thanks!

Does this look good?

Least to Most Basic: I-,F-, HCO3- LiH

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Thanks!

Does this look good?

Least to Most Basic: I-,F-, HCO3- LiH

Yep, good job...rep it

Edited by mississippichem

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