In this experiment, you will titrate solution mixture initially containing carbo

Question

In this experiment, you will titrate solution mixture initially containing carbonate and hydroxide ions. Determine the results in the following two titrations. a. The solution containing both ions is titrated with HCI to the phenolphthalein endpoint. In this case, moles HCI = moles b. If the carbonate ion is first precipitated and then the remaining solution is titrated to the phenolphthalein endpoint with HCI, then in this case, moles HCI=moles c. Which of these titrations will you perform on the leaf jars? Why? Explain what you would do if you inadvertently left the stopcock open while filling the buret with the HCI solution and it spilled out over your bench top.

Explanation / Answer

If a mixture of NaOH and Na2CO3 is titrated using HCl,then the following neutralizations takes place-

NaOH+HCl--->NaCl+H2O

Na2CO3+HCl--->NaHCO3+NaCl

phenolpthalein changes from pink to colorless at pH=8.2, which is the pH range for CO32- and OH- only and not HCO3- ,bicarbonate.

1) moles of HCl=moles of OH-(hydroxide ions) +moles of carbonate ions(CO32-)

2)moles of HCl=moles of OH-(hydroxide ions)[ as carbonate is already precipitated]

3)part 1) as after addition of one equivalent of HCl all carbonate changes to bicabonate ,any further addition of HCl converts bicarbonate to carbonic acid,H2CO3, which exists in equilibrium with CO2 and H2O (carbon dioxide may be expelled out)

4) the HCl can be neutralized by adding mild base sodium carbonate and its acidity reduced.

Related Questions

Navigate

• Browse (All)
• Browse I
• Subjects

---

---

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