I need help with my hw. 13-16 I actually got them wrong my 1st try. 13. What is

Question

I need help with my hw. 13-16 I actually got them wrong my 1st try.

13. What is the pH of a a solution that mixes 30.00 mL ofo. 010 M CH3COOH with 30.00 mL 0.00750 NaCH1CO2? assume that volumes are additive 14. What is the pH of a solution that mixes 20.00 ml of0.10 M NH, with 35.00 mL of0.10 M NH Cl? (assume that volumes are additive) K 1.8 x 10 15. Which of the following combinations could be used to make a buffer? a. HCl. NaC b, NaF, HF c. HNO3, NaClO d. H2S, CH COOH e. NaOH, NH3 16. Which of the following combinations could be used to make a buffer? a. HCl, NH3 b. HNO3, NaNO c. KOH, HCl d. NaOH, NHs e, more than 1 choice

Explanation / Answer

Q13.

find pH for:

V = 30 mL of M = 0.01 M acetic acid

V = 30 mL of M = 0.0075 M of acetate

Note that this will become a buffer

since

weak acid ( acetic acid) is present AND

conjugate base ( acetate ion ) will be present as well from the dissociation of Sodium Acetate

therefore, the equation we must use:

Henderson Hasselbach equation

pH = pKa + log(Acetate/Acetic Acid)

the pKa, from data tables is 4.75

so

pH = 4.75 + log(Acetate/Acetic Acid)

note that

we must recalculate final concentrations

Vtotal = V1+V2 = 30+30 = 60 mL

[Acid] = M1*V1/(Vtotal) = 30*0.01/60 = 0.005 M

[Acetate] = M2*V2/(Vtotal) = 30*0.0075/60 = 0.00375 M

substitute

pH = 4.75 + log(Acetate/Acetic Acid)

pH = 4.75 + log(0.00375 /0.005 )

pH = 4.6250

"Please consider posting multiple questions in multiple set of Q&A. According to Chegg's Q&A Guidelines, we are only allowed to answer to one questions per Q&A."

Related Questions

Navigate

• Browse (All)
• Browse I
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.