please help me understand the soution to a gchem question from destroyer

[skim1988]

In H2O, which of the following is the weakest base?

a)HClO4
b)NH3
c)NH2-
d)OH-
e)ClO4-

the answer is E but shouldn't the answer be A? I understand that ClO4- is a weak base because its conjugate acid is a strong acid but A is a strong acid therefore the weakest base isn't it? what am i missing here?

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[FROGGBUSTER]

In H2O, which of the following is the weakest base?

a)HClO4
b)NH3
c)NH2-
d)OH-
e)ClO4-

the answer is E but shouldn't the answer be A? I understand that ClO4- is a weak base because its conjugate acid is a strong acid but A is a strong acid therefore the weakest base isn't it? what am i missing here?

I thought the same when I came across this problem. I think it's a mistake.

 

[PooyaH]

In H2O, which of the following is the weakest base?

a)HClO4
b)NH3
c)NH2-
d)OH-
e)ClO4-

the answer is E but shouldn't the answer be A? I understand that ClO4- is a weak base because its conjugate acid is a strong acid but A is a strong acid therefore the weakest base isn't it? what am i missing here?

HClO4 is not a base! It's a weak acid.

 

[yappy]

Perchloric acid is a strong acid. Therefore, its conjugate base would be a very very very weak base; because in theory it never accepts an H+.

I think including both the acid and base form is kinda cheap. Base is a function not a classification. To be clear, OH- (a "base") can accept an "H+" or in some conditions donate a proton forming O-- acting as an acid.

EDIT: now that I think about it... Hclo4 functions as an acid not a base. So might as well go with the conjugate base of the known strong acid. E) CL04-.

HClO4 is not a base! It's a weak acid.

 

[PooyaH]

Jesus, yeah HClO4 is a strong acid. My bad. It's been a long day!

 

[PooyaH]

t a base. So might as well go with the conjugate base of the known strong acid. E) CL04-.

Yeah, the reason why it can't be HClO4 is because it's not a base at all.

 

[LetsGo2DSchool]

Jesus, yeah HClO4 is a strong acid. My bad. It's been a long day!

You need a brewski.

 

[skim1988]

oh ok got it! thanks a lot guys.

 

[PooyaH]

You need a brewski.

At this point I need keg.