Need help with number 2, but showed number one to help you understand what I\'m

Question

Need help with number 2, but showed number one to help you understand what I'm working with.

1. Calculate the pH of 0. 1 M HCI. Calculate the pH of 0.1 M acetic acid (Ka 1.8 x 10) Calculate the pH of 0.1 M Na2HPO4 (ONLY consider the first reaction to form H2PO4, Kb = 1.6x10") 2. You will be doing three different titrations. o What do you think will be the major difference in the shapes of the resulting titration curves? ° What do you expect the titration curve to look like at the equivalence point? How will this vary in the three cases? How will this impact the way in which you do the titration? ol li span

Explanation / Answer

A) the pH can be calculated as

pH = -log[H+]

pH = -log[0.1] = 1

B) pH is calculated as pH = -log[H+].

And [H+] =? Ka×C

[H+] = ?1.8×10^-5 × 0.1

= 0.0013638

PH = -log[H+]

= -log[0.0013638]

= 2.865

C)

HPO4-2 + H2O---------------------> H2PO4-   + OH-

0.1                                                  0                0

0.1-x                                              x                 x

Kb = [H2PO4-][OH-]/[HPO4-2]

1.6 x 10^-7 = x^2 / 0.1-x

x^2 + 1.6 x 10^-7 x - 1.6 x 10^-8 = 0

x = 1.26 x 10^-4

[OH-] = x = 1.26 x 10^-4 M

pOH = -log [OH-]

pOH = -log (1.26 x 10^-4 )

pOH = 3.90

pH + pOH = 14

pH + 3.90 = 14

pH = 10.10

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