5. A CHEM 1792 student prepares a dilute solution of sodium hydroxide, NaOH (aq)

Question

5. A CHEM 1792 student prepares a dilute solution of sodium hydroxide, NaOH (aq), starting with 6 M sodium hydroxide. She then titrates a 1.372 g sample of KHP with the dilute sodium hydroxide solution, NaOH (aq), to a phenolphthalein end point. If the titration required 21.84 mL of sodium hydroxide, NaOH (aq), calculate the molar concentration of the sodium hydroxide solution, NaOH (aq). (Remember that KHP is potassium hydrogen phthalate, KHCgH,, NOT potassium hydrogen phosphorus!) a. The student uses the same sodium hydroxide to titrate 10.00 mL of vinegar to a phe- nolphthalein end point. If the titration required 27.48 mL of sodium hydroxide, NaOH (aq), calculate the molar concentration of acetic acid, HC,H,O, (aq), in the vinegar. b.

Explanation / Answer

dilute solution:

mol of KHP = mass/MW = 1.372/204.22 = 0.006718

then...

mol of NaOH = mol fo KHP = 0.006718

[NaOH] = mol of NaOH/ Vol = 0.006718 /(21.84*10^-3) = 0.3076 M

this is the diluted solution

b

mol of NAOH = MV = 0.3076*27.48*10^-3 = 0.0084528 mol of base

mol of acid = 0.0084528 mol of acid

then

[Acid ] = mol/V = (0.0084528 /(10*10^-3) = 0.84528 M

Related Questions

Navigate

• Browse (All)
• Browse 5
• Subjects

---

---

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