Ma Sapling Learning ng mL. The flask shown here contains 1.11 g of acid and a fe

Question

Ma Sapling Learning ng mL. The flask shown here contains 1.11 g of acid and a few drops of phenolphthalein indicator dissolved in water The buret contains 0.220 M NaOH. 10 15 20 25 30 35 40 45 What volume of base is needed to reach the end point of the titration? Number mL base Assuming the acid is monoprotic, what is its molar mass? Click to begin Number Add base to the solution until it just turns pink. You may need to reset the titration if you go past the end point. g/ mol O Previous Give Up & View Solution check Answer Next Exit Hint

Explanation / Answer

Ans. Given,

            Standard NaOH solution, 0.220 M

            1.11 g of unknown acid.

            The acid is monoprotic.

# The volume of base needed to reach the endpoint is NOT mentioned in question. It’s an online simulation experiment and the volume of NaOH must be determined through simulation experiment.

For simplicity of presenting the stepwise solution, let the volume of NaOH consumed to reach the endpoint = 24.71 mL = 0.02471 L

# Mole of NaOH consumed = Molarity x Volume consumed in liters

                                    = 0.220 M x 0.02471 L

                                    = 0.0054362 mol

# Balanced reaction: HA(aq) + NaOH(aq) ------------>NaA(aq) + H2O(l)

In the balanced reaction, 1 mol monoprotic acid is neutralized by 1 mol base.

So,

            Moles of acid = 0.0054362 mol = Moles of NaOH

# Molar mass of acid = Mass of acid sample / Moles of acid

                                    = 1.11 g / 0.0054362 mol

                                    = 204.187 g/ mol

Therefore, molar mass of acid = 204.187 g/ mol

Note: Use the correct experimental volume of NaOH consumed to reach the endpoint and follow the steps to get the correct molar mass of acid.

Related Questions

Navigate

• Browse (All)
• Browse M
• Subjects

---

---

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