KCO Indicator Colof pH Range Indicated Range Overlap Calculated pH Thymol Blue Blue Metuersel Purple Purple Brompbenol blue Purple Methyl Red Yellow Enter pH range in common for all indicators Enter Calculated pH Bromeresol Green Blue Phenol Red Pink Phenol-phhalien Pink Red Cabbage Green This salt contains Choose an item. Calculate the pH of the 0.10 M solution of this salt using the methods described in the Introduction. Record your answers in the Calc pH column. Related Ka and K. values are listec at the end of this lab. In your lab instructions, show your work for this calculation. Take a phon of your work, include your name and date in the photo and insert the photo below. Enter photo of your work here
KCO Indicator Colof pH Range Indicated Range Overlap Calculated pH Thymol Blue Blue Metuersel Purple Purple Brompbenol blue Purple Methyl Red Yellow Enter pH range in common for all indicators Enter Calculated pH Bromeresol Green Blue Phenol Red Pink Phenol-phhalien Pink Red Cabbage Green This salt contains Choose an item. Calculate the pH of the 0.10 M solution of this salt using the methods described in the Introduction. Record your answers in the Calc pH column. Related Ka and K. values are listec at the end of this lab. In your lab instructions, show your work for this calculation. Take a phon of your work, include your name and date in the photo and insert the photo below. Enter photo of your work here
Chapter14: Acids And Bases
Section: Chapter Questions
Problem 10RQ: For oxyacids, how does acid strength depend on a. the strength of the bond to the acidic hydrogen...
Related questions
Question
HOC3- = 4.8x10^-11
Transcribed Image Text:K.CO
Indicator Colot
pH Range Indicated
Range Overlap
Calculated pH
Thymol Blue
Blue
Meturel Purple
Purple
Brompbenol blue
Purple
Methyl Red
Yellow
Enter pl range in
common for all
indicators
Enter Calculated pil
Bromerssal Green
Blue
Phenol Red
Pink
Phenol-phthalien
Pink
Red Cabbage
Green
This salt contains Choose an item.
Calculate the pH of the 0.10 M solution of this salt using the methods described in the
Introduction. Record your answers in the Calc pH column. Related K. and K, values are listed
at the end of this lab. In your lab instructions, show your work for this calculation. Take a photo
of your work, include your name and date in the photo and insert the photo below.
Enter photo of your work here
![For a 0.10 M sodium acetate solution, the calculation is as follows.
C2H3O2 + HL0 S HC2H302 + OH
0.
0.
Initial concentration
Change in conc.
Equilibrium conc.
0.10
+x
+x+
-X
0.10-x
KB(C2H3O2) =
Kw
10-14
%3D
Ka(HCZH302) 18x10-5= 5.56 x 1010
x2
Kb = 5.56 x 10-10 =
x [OH]= 7.46 x 10-6
pOH = 5.13; pH = 8.87
0.10-x
Some ions are amphiprotic meaning they can potentially act as both an acid or as a base when
dissolved in water. They are typically negative jons that also contain acidic hydrogen. They are
also conjugate bases of weak polyprotic acids. Some examples of this type of ion are the
hydrogen oxalate ion, HC2O4 and the monohydrogen phosphate ion, HPO42. The pH for an
amphiprotic ion such as HA can be found using the following equation
pH =
pKai+ pKa2
where Kal is the first dissociation constant for a diprotic acid, H2A and Ka2 is the second
dissociation constant for the conjugate of the diprotic acid, HA".
For example, the ion HC2O4 is derived from the diprotic acid H2C2O4. H2C2O4 has first and
second dissociation constants of Kal = 5.6x10-² and Ka2 = 5.1x10-5. pKal = 1.25 and pKa2 = 4.29.
So to find the pH of a salt solution containing this ion, use the above equation.
1.25+ 4.29
pH =
= 2.77
Certain metal ions can also affect the pH of a solution. They do this by first forming a hydrated
complex ion. If the metal ion is sufficiently small in size and/or highly positively charged, then a
hydrogen ion from one of the water molecules can detach resulting in an acidic solution. For
example, Zn2+ forms the complex Zn(H2O)6²+ in aqueous solution. It can then react as follows.
Zn(H2O)62+ + H2O S Zn(H2O)5(OH)* + H3O*
Ka = 2.5x10-10
The hydronium ion concentration can then be determined using a simple ICE calculation and
from there the pH determined.
If neither ion in a salt affects the pH, then the solvent water is the only substance that affects the
pH and will give a pH = 7.
In rare cases, both ions may affect the pH if the cation is the conjugate acid of a weak base AND
the anion is the conjugate base of a weak acid. In this case, a general determination of acidic,
18](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F48bba008-5eee-4157-b489-6f90113c3fbd%2F9f0cc460-cda2-44c8-8915-8852707d2b12%2Fwmcszz_processed.jpeg&w=3840&q=75)
Transcribed Image Text:For a 0.10 M sodium acetate solution, the calculation is as follows.
C2H3O2 + HL0 S HC2H302 + OH
0.
0.
Initial concentration
Change in conc.
Equilibrium conc.
0.10
+x
+x+
-X
0.10-x
KB(C2H3O2) =
Kw
10-14
%3D
Ka(HCZH302) 18x10-5= 5.56 x 1010
x2
Kb = 5.56 x 10-10 =
x [OH]= 7.46 x 10-6
pOH = 5.13; pH = 8.87
0.10-x
Some ions are amphiprotic meaning they can potentially act as both an acid or as a base when
dissolved in water. They are typically negative jons that also contain acidic hydrogen. They are
also conjugate bases of weak polyprotic acids. Some examples of this type of ion are the
hydrogen oxalate ion, HC2O4 and the monohydrogen phosphate ion, HPO42. The pH for an
amphiprotic ion such as HA can be found using the following equation
pH =
pKai+ pKa2
where Kal is the first dissociation constant for a diprotic acid, H2A and Ka2 is the second
dissociation constant for the conjugate of the diprotic acid, HA".
For example, the ion HC2O4 is derived from the diprotic acid H2C2O4. H2C2O4 has first and
second dissociation constants of Kal = 5.6x10-² and Ka2 = 5.1x10-5. pKal = 1.25 and pKa2 = 4.29.
So to find the pH of a salt solution containing this ion, use the above equation.
1.25+ 4.29
pH =
= 2.77
Certain metal ions can also affect the pH of a solution. They do this by first forming a hydrated
complex ion. If the metal ion is sufficiently small in size and/or highly positively charged, then a
hydrogen ion from one of the water molecules can detach resulting in an acidic solution. For
example, Zn2+ forms the complex Zn(H2O)6²+ in aqueous solution. It can then react as follows.
Zn(H2O)62+ + H2O S Zn(H2O)5(OH)* + H3O*
Ka = 2.5x10-10
The hydronium ion concentration can then be determined using a simple ICE calculation and
from there the pH determined.
If neither ion in a salt affects the pH, then the solvent water is the only substance that affects the
pH and will give a pH = 7.
In rare cases, both ions may affect the pH if the cation is the conjugate acid of a weak base AND
the anion is the conjugate base of a weak acid. In this case, a general determination of acidic,
18
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