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13 Dec 2019

Consider a 300mL sample of 0.250M HCN (Ka=4.9x10^-10). To find the pH, do you need an ice table, can you use the Henderson-Hasselbalch equation, or something else? If an ice table, will it be a Ka or Kb equilibrium? Can you use the small x assumption? Is this a buffer? If something else, then how?

(Need Help Please!!! If possible could you work it out so i can know how to do it)

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Irving HeathcoteLv2

16 Dec 2019

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Related questions

An aqueous solution of 0.080 M KCN is made. At equilibrium this solution will be?

Basic

Neutral

Acidic

Suppose you need to calculate the pH of an aqueous KCN solution. How many of these statements should you be thinking about in advance?

pH should be < 7

don't forget pH = 14 - pOH

pH should be > 7

The mass action equation will be set equal to Ka

I need an ICE table and a Kb or Kw/Ka

pH = -log[x]

-log[x] = pOH not pH

What reaction would you use in an ICE table to calculate the pH of a KCN solution? CN- + H2O â HCN + H3O+

CN- + H2O â HCN + OH-

H+ + OH- â H2O

KCN (s) â K+ + CN-

What is the pH of a 0.080 M KCN solution.

The Ka for HCN is 8.0Ã10-10

Fill out the whole table, you do not have to show your work on all of them, just show your work on 4 different kinds, example:

Problem #1: an acid that I measured the pH, we turn that into hydrogen ion concentration and fill out the table.

Problem #2: an acid where I did not measure the pH, in which case you start by looking up kA, then fill out the table

Problem #3: a base where I measured the pH turn that into hydroxide concentration and fill out the table,

Problem #4: a base where I did not measure the pH, then you have to find kB and fill out the table.

You only have to show work for each one of these and the rest can be done without any work.

In that table if you were to look at "Exp pH" you could see that some of them are crossed over and another pH is written, those ones are called "measured" for the measured columns you have to fill out "Theo Ka or Kb" and the "%error" as well. For the non measured rows, you do not have to fill out "Theo Ka or Kb" and the "%error."

NOTES:

1) For the Conjugate Acid and Conjugate Base, do not put H+, OH-. If itâs a weak acid, put that weak acid. For Conjugate base, then put the weak base. If the compound was a weak base, then put that thing in there, then put the conjugate acid in the other column. And do not include any spectator ions.

2) Do not bother to use the ice table to determine X, values for Ka or Kb can be looked up online.

3) In the case of nitrate ion, we cannot Kb, we can only look up Ka for its conjugate acid.

4) 7 of them have their pH measured. And the other 7 do not and that should be looked up.

Fill out the whole table, you do not have to show your work on all of them, just show your work on 4 different kinds, example:

Problem #1: an acid that I measured the pH, we turn that into hydrogen ion concentration and fill out the table.
Problem #2: an acid where I did not measure the pH, in which case you start by looking up kA, then fill out the table
Problem #3: a base where I measured the pH turn that into hydroxide concentration and fill out the table,
Problem #4: a base where I did not measure the pH, then you have to find kB and fill out the table.

You only have to show work for each one of these and the rest can be done without any work.

NOTES:
1) For the Conjugate Acid and Conjugate Base, do not put H+, OH-. If itâs a weak acid, put that weak acid. For Conjugate base, then put the weak base. If the compound was a weak base, then put that thing in there, then put the conjugate acid in the other column. And do not include any spectator ions.

2) Do not bother to use the ice table to determine X, values for Ka or Kb can be looked up online.

3) In the case of nitrate ion, we cannot Kb, we can only look up Ka for its conjugate acid.

4) 7 of them have their pH measured. And the other 7 do not and that should be looked up.