Help with orgo please The pK, of 4-nitrophenol is 7.15 and that of 2.5-dinitroph

Question

Help with orgo please The pK, of 4-nitrophenol is 7.15 and that of 2.5-dinitrophenol is 5.15. would you expexy either of these substances to dissolve (react) in aqueous sodium bicarbonate (NaHCO2) solution? Note that the pK2 of carbonic acid, H2CO3, is 6.36. Hint: for each compound, draw an acid-base reaction and determine the position of the quilibruim. Calculate the molarity (mcl/L) of 30% aqueous NaOH sloution. Assume that a 30% solution contains 30 grams of solute per 70g of solvent. the density of the solution is 1.33 g/mL. What volume of 6.0 M aqueous HCI solution is needed to neutralize 25mL. of 1.3 M aqueous NaOH solution?

Explanation / Answer

6-N1V1 = N2V2

V1= N2V2/N1 = 25 x1.3 /6 = 5.416ml

5-d=1.33g/ml =1330g/L

   30% NaOH =30% of 1L is 0.3 L

density = mass/volume => mass= density x volume = 1330x 0.3 = 399g

Mw of NaOH =40g/mol

mole of NaOH = 399/40

molarity = mole /liter = 399/40 /1 = 9.98M

4-pKa = -logKa

For the first molecule (NO2C6H5OH):
-log Ka = 7.15, logKa = -7.15, Ka = 10^-7.15

And for the other molecule ((NO2)2C6H4OH):
-log Ka = 5.15, log Ka = -5.15, Ka = 10^-5.15

((NO2)2C6H4OH) has the bigger value for Ka and is therefore the stronger acid.

H2CO3(aq) <=> H+(aq) + HCO3-(aq) it is a weak acid.

In order to dissolve in sodium bicarbonate solution, the nitrophenol molecule would have to be able to donate H+(aq) ions to the above system.

thus ((NO2)2C6H4OH) can dissolved in H2CO3 . Since it can donate H+due to strong acid.

Related Questions

Navigate

• Browse (All)
• Browse H
• Subjects

---

---

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