What are colligative properties

[ "article:topic", "mole fraction", "vapor pressure", "van\'t Hoff factor", "showtoc:no", "colligative properties", "vapor pressure depression", "ionic solutes", "Raoult\u2019s law", "license:ccbyncsa", "authorname:anonymous", "program:hidden", "licenseversion:30", "source@https://2012books.lardbucket.org/books/beginning-chemistry" ] Learning Objective • Determine the colligative properties of solutions of ionic solutes. Previously, we considered the colligative properties of solutions with molecular solutes. What about solutions with ionic solutes? Do they exhibit colligative properties? There is a complicating factor: ionic solutes separate into ions when they dissolve. This increases the total number of particles dissolved in solution and increases the impact on the resulting colligative property. Historically, this greater-than-expected impact on colligative properties was one main piece of evidence for ionic compounds separating into ions (increased electrical conductivity was another piece of evidence). For example, when NaCl dissolves, it separates into two ions: \[\ce\) Ideal van 't Hoff Factors for Ionic Compounds Compound i NaCl 2 KBr 2 LiNO 3 2 CaCl 2 3 Mg(C 2H 3O 2) 2 3 FeCl 3 4 Al 2(SO 4) 3 5 The ideal van 't Hoff factor is equal to the number of ions that form when an ionic compound dissolves. Exercise \(\PageIndex\) What is the van 't Hoff factor for Fe(NO 3) 3? Answer 4 It is the "ideal" van 't Hoff factor because this is what we expect from the ionic formu...

11 Colligative Properties Michael Mombourquette 11.1: Introduction Colligative properties ⇨ Properties of solutions which depend on the number of solute particles but not on their nature. Examples of colligative properties are: • Vapour Pressure lowering of a solution • Boiling Point elevation • Freezing Point depression • Osmotic Pressure 11.2: Vapour Pressure Lowering The commonality in these properties is that the effects are entropy effects. Take, for example, the vapour pressure of a pure liquid versus one in which a solute has been dissolved. In the former case, the difference in entropy for the phase-change reaction is greater than that for the latter since the process of dissolving the solute into the liquid has slightly increased the entropy of the liquid (more random since the solute is spacing out the solvent molecules a bit). Hence, the vapour pressure of the pure liquid is higher than that of the solution. where P solvent = vapour pressure of the solvent in solution, and P* solvent = vapour pressure of the pure solvent. Recall that the total pressure of a solution is the sum of the partial pressures of the solvent and solute If the solute is non-volatile (no vapour pressure: P* solute = 0) then the total vapour pressure of solution is To see this in graphical form, see the phase diagram for pure water, below. Three lines are present indicating the phase transition (read equilibrium) between solid, liquid and gas. Where all three lines meet is the triple point ...

How Colligative Properties Work When a solute is added to a solvent to make a solution, the dissolved particles displace some of the solvent in the liquid phase. This reduces the concentration of the solvent per unit of volume. In a dilute solution, it doesn't matter what the particles are, just how many of them are present. So, for example, dissolving CaCl 2 completely would yield three particles (one calcium ion and two chloride ions), while dissolving NaCl would only produce two particles (a sodium ion and a chloride ion). The calcium chloride would have a greater effect on colligative properties than the table salt. This is why calcium chloride is a more effective de-icing agent at lower temperatures than ordinary salt. • Colligative properties depend only on solute concentration and temperature, not on the nature of the solute particles. • Constitutional properties depend on the molecular structure of the solute particles in a solution. • Additive properties are the sum of all the properties of the particles. Additive properties are dependent on the molecular formula of the solute. An example of an additive property is mass. Helmenstine, Anne Marie, Ph.D. "Colligative Properties of Solutions." ThoughtCo, Feb. 16, 2021, thoughtco.com/definition-of-colligative-properties-604410. Helmenstine, Anne Marie, Ph.D. (2021, February 16). Colligative Properties of Solutions. Retrieved from https://www.thoughtco.com/definition-of-colligative-properties-604410 Helmenstine, Anne Ma...

https://chem.libretexts.org/@app/auth/3/login?returnto=https%3A%2F%2Fchem.libretexts.org%2FBookshelves%2FPhysical_and_Theoretical_Chemistry_Textbook_Maps%2FSupplemental_Modules_(Physical_and_Theoretical_Chemistry)%2FPhysical_Properties_of_Matter%2FSolutions_and_Mixtures%2FColligative_Properties%2FBoiling_Point_Elevation \( \newcommand\) molal K f (freezing point constant) Osmotic Pressure \(P\) molar RT The determination of colligative properties allows us to determine the concentration of a solution and calculate molar masses of solutes Boiling Point Elevation The boiling points of solutions are all higher than that of the pure solvent. Difference between the boiling points of the pure solvent and the solution is proportional to the concentration of the solute particles: \[\Delta\) is the boiling point elevation, \(K_b\) is the boiling point elevation constant, and m is the molality (mol/kg solvent) of the solute.

Contents • 1 Colligative Properties • 2 Relative Lowering in Vapour Pressure • 3 Relative lowering of vapour pressure-a colligative property • 4 Determination of Molar Mass of a Solute from Relative Lowering in Vapour Pressure • 5 Elevation in Boiling Point • 6 Depression in freezing point- a colligative property • 7 Determination of Molar mass of solute from Depression in Freezing point temperature Colligative Properties The properties of the solutions which depend only on the number of solute particles but not on the nature of the solute are called Colligative properties. The four important colligative properties are: (i) Relative lowering in vapour pressure (ii) Elevation in boiling point (iii) Depression in freezing point (iv) Osmotic pressure. Relative Lowering in Vapour Pressure When a non-volatile solute is added to a solvent, the vapour pressure of the solution decreases. Let x A be the mole fraction of the solvent, x B be the mole fraction of the solute and p be the vapour pressure of the pure solvent and p be the vapour pressure of solution. Since solute in non-volatile, there will be no contribution of solute to the vapour pressure and the vapour pressure of the solution will be only due to the solvent. Therefore, the vapour pressure of the solution (p) will be equal to the vapour pressure of the solvent (p A), over the solution, i.e., p=p A But, according to Raoult’s law, the vapour pressure of solvent is equal to the product of its vapour pressure in pure stat...

Colligative Property The colligative properties of a solution are defined as the properties which are determined by the number or the mole fraction of components (solutes and solvent) in the solution and are independent of the nature of the solutes and their molecular weights. From: Comprehensive Polymer Science and Supplements, 1989 Related terms: • Energy Engineering • Molecular Weight • Mols • Boiling Point Elevation • Freezing Point Depression • Mole Fraction • Osmolarity • Nanosheet Polymer Characterization Kenji Kamide, in Comprehensive Polymer Science and Supplements, 1989 4.1Introduction The colligative properties of a solution are defined as the properties which are determined by the number or the mole fraction of components (solutes and solvent) in the solution and are independent of the nature of the solutes and their molecular weights. If any physical quantities belonging to the colligative property ( i.e. the colligative quantity) can be measured under thermodynamic equilibrium and also if the total weight of solute dissolved in a given solution is known, the molecular weight of the nonvolatile solute (or in the case of a nonuniform solute, the average molecular weight) can be determined. Unfortunately, both the osmotic pressure of the real solution and the vapor pressure of the vapor phase in equilibrium with the real solution are significantly influenced, in the finite concentration range of the solute, by the solute-solvent interaction and are not unique fu...