Methanol, CH 3 OH, is a nonelectrolyte; hypochlorous acid, HClO, is a weak elect

ID: 1045927 • Letter: M

Question

Methanol, CH3OH, is a nonelectrolyte; hypochlorous acid, HClO, is a weak electrolyte; and iron(III) sulfate, Fe2(SO4)3, is a strong electrolyte. What are the solute particles present in aqueous solutions of each compound? (Select all that apply.)

OH -O2-CH3O-CH3OHCH3OH2+H+

OH -ClO-HCl2+HClOO2-H+

SO43-Fe2+S2O42-Fe2(SO4)3SO42-Fe3+

If 0.1 mol of each compound is dissolved in solution, which one contains about 0.5 mol of solute particles, which contains 0.1 mol of solute particles, and which contains somewhere between 0.1 and 0.2 mol of solute particles?

methanol hypochlorous acid iron(III) sulfate

OH -O2-CH3O-CH3OHCH3OH2+H+

OH -ClO-HCl2+HClOO2-H+

SO43-Fe2+S2O42-Fe2(SO4)3SO42-Fe3+

Explanation / Answer

Methanol is a non-electrolyte and will not ionize in an aqueous solution. Hence, an aqueous solution of methanol will contain undissociated methanol (CH3OH) molecules. In addition, water is poorly ionized in an aqueous solution to give H+ and OH-.

Hypochlorous acid (HClO) is a weak electrolyte and ionizes partly in aqueous solution to give H+ and OCl- ions. Since HClO is a weak electrolyte, hence, undissociated HClO molecules are also present in an aqueous solution. In addition, OH- resulting from the ionization of water will be present in an aqueous solution of HClO.

Fe2(SO4)3 is a strong electrolyte and ionizes completely in aqueous solution to provide Fe3+ and SO42- ions. Since we have a strong electrolyte, no undissociated molecules are present. In addition, water ionizes to give H+ and OH- ions.

CH3OH

HClO

Fe2(SO4)3

Ions present in aqueous solutions

CH3OH, H+, OH-

HClO, H+, ClO-, OH-

Fe3+, SO42-, H+, OH-

Consider the ionizations of the weak and strong electrolytes.

HClO (aq) -------> H+ (aq) + ClO- (aq)

Fe2(SO4)3 (aq) ------> 2 Fe3+ (aq) + 3 SO42- (aq)

Since 1 mole of Fe2(SO4)3 ionizes completely to give 2 moles of Fe3+ and 3 moles of SO42-(total 5 moles of ions), hence, 0.1 mole Fe2(SO4)3 will provide 0.5 moles of ions.

CH3OH is completely unionized in solution; hence, 0.1 mole CH3OH in solution will yield only 0.1 mole solute particles (as undissociated molecules).

Complete ionization of 1 mole of HClO would have given 2 moles of ions; however, HClO is a weak electrolyte and partially ionized. Hence, 1 mole HClO will furnish less than 2 moles of ions. Consequently, 0.1 mole HClO will give somewhere between 0.1 mole and 0.2 mole ions in aqueous solution.