Question

part a: Colligative properties are only incidentally affected by chemical properties of substances. The most important point is that colligative properties are dependent on the number of free solute particles in solution, not the specific nature of those particles. When dissolving substances, it is important to understand how many particles are released by that substance. One mole of sodium chloride produces two moles of dissolved particles:one mole of Na⁺(aq) and one mole of Cl^-(aq), while one mole of sucrose produces only one mole of C₁₂H₂₂O₁₁(aq) in solution. Remember covalent bonds do not break when a molecular compound that is not an acid dissolves in a solvent.

Why would the effect on any of the colligative properties be twice as great for the ionic compound, sodium chloride, as it would for the molecular (covalent) compound, sucrose?

	a.	NaCl dissolves to release one NaCl unit . Sucrose dissolves to release one molecule per unit.
	b.	NaCl dissolves to release two ions per unit: Na+ and Cl- . Sucrose dissolves to release two C6H11O6.5 molecules per unit.
	c.	NaCl dissolves to release two ions per unit: Na0 and Cl0. Sucrose dissolves to release 12 C, 22H and 11O atoms per unit.
	d.	NaCl dissolves to release two ions per unit: Na+ and Cl- . Sucrose dissolves to release one molecule per unit.

part b: Acetone is a water soluble molecular compound, if 0.193mol C₃H₆O is dissolved in water how many moles of particles will be released into solution? Enter the numeric answer in decimal notation, include the correct unit in the proper case.

part c: Calcium chloride is a water soluble ionic compound, if 0.075 mol CaCl₂ are dissolved in water, how many moles of particles will be released into solution? Enter the numeric answer in decimal notation, include the correct unit in the proper case.

Answer 1

a) Why would the effect on any of the colligative properties be twice as great for the ionic compound, sodium chloride, as it would for the molecular (covalent) compound, sucrose?

The best answer is the amount of species in solution

NaCl is ionic so it is Na+ and Cl- cation/anion pair per unit NaCl

therefore,expect 2x effect due to:

NaCl dissolves to release two ions per unit: Na+ and Cl- . Sucrose dissolves to release one molecule per unit. b) 1 mol of acetone --> 1 mol released 0.193 mol of acetone will be accoutned overall c) CaCl2 = Ca+2 and 2Cl-   total ions 1+2 = 3 then.. 0.075* 3= 0.225 ions per 0.075 mol of CaCl2