April 18, 2024, 08:00:49 PM
Forum Rules: Read This Before Posting


Topic: Salts and Acids in solutions  (Read 9107 times)

0 Members and 1 Guest are viewing this topic.

sweetdaisy186

  • Guest
Salts and Acids in solutions
« on: July 31, 2005, 06:20:14 PM »
I am having so much trouble with these kinds of questions. Maybe I just need another perspective. Thanks!

1. Which of the following is the strongest acid in aqueous solution?
  a) H2S      b) H2O      c) NH3      d) CH4      
2. Which of the following salts will have the highest pH in aqueous solution?
      a) NaClO   b) KBrO2   c) KClO3   d) NaBrO   

3. Addition of NaCN to a solution of HCN will
      a) increase pH   b) decrease pH   c) have no effect on pH

4. Which of the following salts will produce a neutral solution?
      a) NaHS   b) NH4Cl   c) LiHSO4   d) KNO3   e) all are neutral

My problem with number 2 is that wouldn't my choices be narrowed to either A or D since sodium is a salt? And then I get confused and I can't pick between the two of them. For 3 I am thinking that it will decrease, and for the last one I am thinking A. I hope I am doing this correctly. Thanks again!




Offline sdekivit

  • Chemist
  • Full Member
  • *
  • Posts: 403
  • Mole Snacks: +32/-3
  • Gender: Male
  • B.Sc Biomedical Sciences, Utrecht University
Re:Salts and Acids in solutions
« Reply #1 on: August 01, 2005, 04:41:40 AM »
1)2) do something with the inductive effect.

3) CN(-) is an acid or base? If you know that the answer is easy.

4) salts of a strong acid will give a neutral solution.

Offline Borek

  • Mr. pH
  • Administrator
  • Deity Member
  • *
  • Posts: 27652
  • Mole Snacks: +1800/-410
  • Gender: Male
  • I am known to be occasionally wrong.
    • Chembuddy
Re:Salts and Acids in solutions
« Reply #2 on: August 01, 2005, 04:45:44 AM »
1. Which of the following is the strongest acid in aqueous solution?
  a) H2S  b) H2O  c) NH3  d) CH4

Compare Ka values.

Quote
2. Which of the following salts will have the highest pH in aqueous solution?
      a) NaClO  b) KBrO2  c) KClO3  d) NaBrO

Think about hydrolisis - strong bases can be put aside. Do you know any rules governing strength of oxoacids? Which two will be the weakest? Do you know general trends describing changes of acid strength in the periodic table?

Quote
3. Addition of NaCN to a solution of HCN will
      a) increase pH  b) decrease pH  c) have no effect on pH

Before - dissociation, after addition - buffer.

Quote
4. Which of the following salts will produce a neutral solution?
      a) NaHS  b) NH4Cl  c) LiHSO4  d) KNO3  e) all are neutral

To be precise - none will be neutral :) But that's the higher chemistry ;)

But for this question - strong acids and strong bases don't hydrolise in salts. Presence of every weak acid or weak base, or of any not fully neutralized acid will change pH.
« Last Edit: August 01, 2005, 05:19:36 AM by Borek »
ChemBuddy chemical calculators - stoichiometry, pH, concentration, buffer preparation, titrations.info

sweetdaisy186

  • Guest
Re:Salts and Acids in solutions
« Reply #3 on: August 01, 2005, 09:51:29 PM »
1. We aren't allowed to use our Ka values to compare them. He wants us to be able to look at them and know. What is the inductive effect? I don't think we have talked about that. However, looking at the P table I am thinking H2S.

2. Rules about strength of oxoacids go left and down right, while it is the opposite for bases correct?. Going with that I will say KClO3.

3. Okay, so then it would increase correct?

4. The KNO3 would produce the neutral solution.

These are my guesses, I hope I am understanding them correclty! Thank you both for all your *delete me*

Sponsored Links