Is the pH greater than, equal to. or less than 7 after the neutralization of eac

Question

Is the pH greater than, equal to. or less than 7 after the neutralization of each of the following pairs of acids and bases? (a) HI and NaOH (b) HOCI and Ba(OH)_2 (c) HNO_3 and aniline (C_6H_5NH_2) (d) Benzoic acid (C_4H_5CO_2H) and KOH Does the pH increase, decrease, or remain the same on the addition of each of the following? (a) NH_4NO_3 to an NH_3 solution (b) Na_2CO_3 to an NaHCO_3 solution (c) NaCIO_4 to an NaOH solution Calculate the pH of a buffer solution that is 0.20 M in HCN and 0.12 M in NaCN. Will the pH change If the solution is diluted by a factor of 2? Explain. Calculate the pH and the concentrations of all species present (H_3O^+, F^-, HF, CI^-, and OH^-) in a solution that contains 0.10 M HF (K_a = 3.5 x 10^-6) and 0.10 M HCI.

Explanation / Answer

2)

a. equal to 7

i believe its a base + acid which is aneutralization reaction. so it would yield salt + water.

NaI + H20
for net ionic u have to serpate the soluble compounds into their ions and then cancel out whatever ions are similar on each side

Na+ + OH- + H+ + I- ---> H20 + Na+ + I-

net ionic: OH- + H+ ---> H20

b) equal to 7

c) acidic pH will less than 7

d) basic pH will greater than 7

3)

a. decrease

NH4NO2 is acidic and NH3 is besic

b. increase

c. decrease

4.You use the Henderson - Hasselbalch equation for calculation of pH of buffer solution
pKa HCN = 9.21

pH = pKa + log ( [salt]/[acid])
pH = 9.21 + log (0.12/0.20)
pH = 9.21 + log 0.6
pH = 9.21 - 0.22
pH = 8.98

5.

HF ----> H+ + F-
Ka = [H+][F-] / [HF] = 3.5 x 10-4

Let s = amount of HF that dissociates (ionizes)
[H+] = x
[F-] = x
[HF] = 0.10 - x

3.5 x 10^-4 = (x)(x) / (0.10 - x)
x2 = (0.10 - x) x 3.5 x 10^-4
X2 = 3.5x10-5 - 3.5x10-4 X
X = 0.00574
[H+] = [F-] = 0.00574 M = [H3O+]

pH = -log[H+]

pH = 2.24

pH of HCl = 1

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