Question 18. HPO_4 ^2- is an acid and H_2O is its conjugate base. H_2O is an aci

Question

Question 18. HPO_4 ^2- is an acid and H_2O is its conjugate base. H_2O is an acid and HPO_4^2-is its conjugate base. HPO_4 ^2- is an acid and OH^- is its conjugate base. A buffer made from equal amounts of nitrous acid and nitrite ion (HNO_2, NO_2) has a buffer capacity of 0.050 mol/L. If 0.035 mol of HCI is added to 150 m L of the buffer solution, what will happen to the pH? (Assume the total buffer + acid volume is still close to 150 m L) The pH will be slightly more basic. The pH will be slightly more acidic. The pH will remain exactly the same. The pH will become very acidic. The pH will become very basic. What is the pH of a buffer that is 0.29 M in acetic acid, HC_2 H_3 O_2, and 0.68 M in sodium acetate NaC_2 H_3 O_2 at 25 degree C? K_a of acetic acid is 1.8 x 10^-5. 1.26 4.37 4.74 2.25 5.11 Complete the statement: The weak acid formic acid is titrated with a strong base. At the equivalence point of the titration, the solution. is acidic. is neutral(pH 7). has excess moles of the weak acid. is basic. has excess moles of the strong base.

Explanation / Answer

18)

if buffer apply

pH = pKA +log(conjugate/acid)

[Acid] = 0.29

[conjguat] = 0.68

then

pKa = -logKa = -log(1.8*10^-5) = 4.7447

pH = pKA +log(conjugate/acid) = 4.7447 + log(0.68/0.29)

pH = 5.1148

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