Question

1) Which statement below is correct (true)?

a) Since HNO2 is a stronger acid than HF it must have a greater pKa.
b) Since HOCℓ is a stronger acid than HCN, then OCℓ– is a stronger base than CN–.
c) The dissociation (or ionization) of HOCℓ in water is HOCℓ + H2O º HCℓ + 2OH–.
d) The pH of a 0.10 M solution of acetic acid (Ka = 1.8 x 10-5) will be higher than the pH of a 0.10 M solution of formic acid (Ka = 1.8 x 10-4).
e) If the Kb for CH3NH2 is 5.0 x 10-4, the Ka for CH3NH3+ is 2.0 x 10-5.


My answer is that the pH of acetic acid will be higher than formic acid.

2)Which of the following is a Bronsted-Lowry base but not a Lewis base?

H2O, CN^-^, HSO4^-^, NH3, all choices are both B/L and Lewis base.

I know that H2O and NH3 are lewis base but I am not sure about CN^-^ and CO3^2-^. I think that CO3^2-^ is the answer that is not a lewis base.

Would you agree with my answers? Thank you for checking my answers.

Answer 1

#1 is ok.
#2. You don't have carbonate listed.

Answer 2

Oh Im sorry I missed that. CO3^2-^ is an answer listed. I was able to find that CN^-^ is a BL base but Im still not sure if it is a Lewis base. I do not think it is.

Answer 3

:C:::N:
CN^- is a B.L base because it can add a proton as H:C:::N:
and it has those lone pairs so it can donate electrons, too.

Answer 4

Ok so the only one im still not sure about is CO3^2-^. The -2 are lone pairs so I guess it is both Lewis and BL.

Answer 5

I think that's right.