Question

In: Chemistry

Phosphorous acid, H3PO3(aq), is a diprotic oxyacid that is an important compound in industry and agriculture....

Phosphorous acid, H3PO3(aq), is a diprotic oxyacid that is an important compound in industry and agriculture.

Calculate the pH for each of the following points in the titration of 50.0 mL of a 1.5 M H3PO3(aq) with 1.5 M KOH(aq).

pKa1= 1.30

pKa2= 6.70

(a) before addition of any KOH =_____number

(b) after addition of 25.0 mL of KOH = ______number

(c) after addition of 50.0 mL of KOH = ______number

(d) after addition of 75.0 mL of KOH =_______number

(e) after addition of 100.0 mL of KOH=______number

please explain how you got each! thanks so much

Solutions

Expert Solution

H3PO3 millimoles = 50 x 1.5 = 75

a) Before any addition of KOH :

H3PO3 ---------------------> H+ +   H2PO3-

1.5 0             0

1.5- x                                   x              x

Ka1 = [H+][H2PO3-] / [H3PO3]

0.05 = x^2 / 1.5 - x

x = 0.25

[H+] = 0.25 M

pH = -log [H+] = -log [0.25]

       = 0.6

pH = 0.6

b) after addition of 25.0 mL KOH

it is first equivaelce point

pH = pKa1 = 1.30

pH = 1.30

c ) addition of 50.0 mL KOH

it is first equivalence point

pH = 1/2 (pKa1 + pKa2)

pH =1/2 (1.30 + 6.70)

pH = 4.0

d) 75.0 mL KOH

it is seond half equivalece point

pH = pKa2

pH = 6.70

4) 100.0 mL KOH

it is second equivalece point

HPO3^-2 millimoles = 100 x 1.5 = 150

HPO3^-2 molarity = 150 / (50 +100) = 1.0 M

HPO3^-2 + H2O ------------------> H2PO4- + OH-

1.0 -x                                           x                x

Kb2 = x^2 / 1.0-x

5.01 x 10^-8 = x^2 / 1.0 -x

x^2 + 5.01 x 10^-8 - 5.01 x 10^-8 = 0

x = 2.24 x 10^-4

[OH-] = 2.24 x 10^-4 M

pOH = -log[OH-] = -log (2.65 x 10^-4 )

pOH = 3.65

pH + pOH = 14

pH = 10.35


Related Solutions

Phosphorous acid, H3PO3(aq), is a diprotic oxyacid that is an important compound in industry and agriculture....
Phosphorous acid, H3PO3(aq), is a diprotic oxyacid that is an important compound in industry and agriculture. Calculate the pH for each of the following points in the titration of 50.0 mL of a 1.5 M H3PO3(aq) with 1.5 M KOH(aq). pKa1= 1.30 pKa2= 6.70 (a) before addition of any KOH =_____number (b) after addition of 25.0 mL of KOH = ______number (c) after addition of 50.0 mL of KOH = ______number (d) after addition of 75.0 mL of KOH =_______number...
Phosphorous acid, H3PO3(aq), is a diprotic oxyacid that is an important compound in industry and agriculture...
Phosphorous acid, H3PO3(aq), is a diprotic oxyacid that is an important compound in industry and agriculture pka1=1.3 pka2=6.70 Calculate the pH for each of the following points in the titration of 50.0 mL of a 2.7 M H3PO3(aq) with 2.7 M KOH(aq) a) before addition of any KOH (b) after addition of 25.0 mL of KOH (c) after addition of 50.0 mL of KOH (d) after addition of 75.0 mL of KOH (e) after addition of 100.0 mL of KOH...
Phosphorous acid, H3PO3(aq), is a diprotic oxyacid that is an important compound in industry and agriculture....
Phosphorous acid, H3PO3(aq), is a diprotic oxyacid that is an important compound in industry and agriculture. pKa1 = 1.30 pKa2 = 6.70 Calculate the pH for each of the following points in the titration of 50.0 mL of a 2.7 M H3PO3(aq) with 2.7 M KOH(aq). A) before addition of any KOH B) after addition of 25.0 mL of KOH C) after addition of 50.0 mL of KOH D) after addition of 75.0 mL of KOH E) after addition of...
Phosphorous acid, H3PO3(aq), is a diprotic oxyacid that is an important compound in industry and agriculture.Calculate...
Phosphorous acid, H3PO3(aq), is a diprotic oxyacid that is an important compound in industry and agriculture.Calculate the pH for each of the following points in the titration of 50.0 mL of a 3.0 M H3PO3(aq) with 3.0 M KOH(aq). (a) before addition of any KOH (b) after addition of 25.0 mL of KOH (c) after addition of 50.0 mL of KOH (d) after addition of 75.0 mL of KOH e) after addition of 100.0 mL of KOH
Phosphorus acid, H3PO3(aq), is a diprotic oxyacid that is an important compound in industry and agriculture....
Phosphorus acid, H3PO3(aq), is a diprotic oxyacid that is an important compound in industry and agriculture. pKa1= 1.30 pKa2= 6.70 Calculate the pH for each of the following points in the titration of 50.0 mL of a 2.4 M H3PO3(aq) with 2.4 M KOH(aq). a. before addition of any KOH b. after addition of 25.0 mL of KOH c. after addition of 50.0 mL of KOH d. after addition of 75.0 mL of KOH. e. after addition of 100.0 mL...
1) Phosphorous acid, H3PO3, is actually a diprotic acid for which Ka1= 5.0 × 10-2 and...
1) Phosphorous acid, H3PO3, is actually a diprotic acid for which Ka1= 5.0 × 10-2 and Ka2= 2.0 × 10-7. What are the values of [H+], [H2PO3-], and [HPO32-] in a 6.0 M solution of H3PO3? What is the pH of the solution? 2) What is the pH of a 1.6 M solution of Na3PO4? In this solution, what are the concentrations of HPO42-, H2PO4-, and H3PO4? 3)Ascorbic acid (vitamin C) is a diprotic acid, H2C6H6O6. Calculate [H+], pH, and...
Oxalic acid , HOOCCOOH (aq) , is a diprotic acid with Ka1= 0.056 and Ka2=1.5x10-4. Determine...
Oxalic acid , HOOCCOOH (aq) , is a diprotic acid with Ka1= 0.056 and Ka2=1.5x10-4. Determine the pH of a 0.12 M oxalic acid solution. HOOCCOOH(aq) = HOOCCOO-(aq) + H+(aq) HOOCCOO-(aq) = -OOCCOO-(aq) + H+(aq)
Tartaric acid (“H2Tart”, M.W. = 176.13) is a diprotic acid that is important in food preparation....
Tartaric acid (“H2Tart”, M.W. = 176.13) is a diprotic acid that is important in food preparation. (See McMurray & Fay Appendix C for its Ka values.) A solution of tartaric acid is produced by dissolving 2.90 g of H2Tart in 1.000 L of water. What are the equilibrium concentrations of H2Tart, HTart-, Tart2-, and H+ in this solution?
Sulfur dioxide is quite soluble in water: SO2(g)+H2O(l)⇌H2SO3(aq)K=1.33 The H2SO3 produced is a weak diprotic acid...
Sulfur dioxide is quite soluble in water: SO2(g)+H2O(l)⇌H2SO3(aq)K=1.33 The H2SO3 produced is a weak diprotic acid (Ka1 = 1.5×10−2, Ka2 = 6.3×10−8) Part A Calculate the pH in a solution prepared by continuously bubbling SO2 at a pressure of 1.00 atm into pure water. Express your answer using two decimal places. Part B Calculate the concentration of H2SO3. Express your answer using three significant figures. Part C Calculate the concentration of HSO3−. Express your answer using two significant figures. Part...
ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT