Freezing point depression and molar mass determination. Colligative properties include vapor pressure, boiling point, freezing point, and osmotic pressure. Selfgeneration of colligative properties at hydrophilic surfaces. This powerpoint presentation explains what colligative properties are and explains the causes of freezing point depression and boiling point. Colligative properties, such as osmotic pressure and freezing point depression, depend on the number of solute particles in a solution and may be employed in the determination of numberaverage molecular weight, m. The colligative properties include vapor pressure lowering, boiling point elevation, freezing point depression, and osmotic pressure. Determination of the molar mass of a compound by freezing point depression. Colligative properties definition, types, examples. Ppt colligative properties powerpoint presentation. Freezing point depression phase diagram and the lowering of the freezing point. Colligative properties are properties of solution that depend only on how much solute is dissolved not on what type of solute is dissolved. Colligative properties such as freezing point depression can be used to determine molar masses. Freezing point depression solution has lower freezing point that solvent given by. The greener procedure substitutes the nontoxic, noncarcinogenic compounds stearic, myristic, lauric, and palmitic acids for the less benign aromatic compounds pdichlorobenzene, benzil, biphenyl, naphthalene, and nitrotoluene.
Colligative properties are those that depend on the concentration of particles in a solution, not upon the identity of those particles. Colligative properties ch102 general chemistry, spring 2014, boston university there are four colligative properties. What influence does adding more solute to a solvent hae on the freezing point and boiling point of the resultant solution compared to the pure solvent. In 1884 jacobus henricus vant hoff introduced another term into the freezing point depression and boiling point elevation expressions to explain the colligative properties of solutions of compounds that dissociate when they dissolve in water. Solutions 05 i colligative property elevation in boiling. Colligative properties depend on the number of particles present in a solution, but not on the identity of the particles. In chemistry, colligative properties are those properties of solutions that depend on the ratio of. The objective of this experiment is to determine the molar mass of an unknown solute by measuring the freezing point depression of a solution of this solute in a solvent as compared to the freezing point of the pure solvent. At this temperature, the gaseous and liquid states of. In a pure solvent, the entire surface is occupied by the molecules of the solvent. For example, adding a pinch of salt to a cup of water makes the water freeze at a lower temperature than it normally would, boil at a higher temperature. Colligative properties by definition a colligative property is a solution property a property of mixtures for which it is the amount of solute dissolved in the solvent matters but the kind of solute does not matter. Colligative properties include vapor pressure lowering, boiling point elevation, freezing point depression.
Other examples of colligative properties include boilingpoint elevation and osmotic pressure. The more nonwater particles there are, the more the freezing point is lowered. Give an example of a colligative property other than freezing point depression. Freezing point depression and colligative properties materials 12 cup milk 12 cup whipping cream heavy cream or substitute 4 tbsp. For example, lets suppose you are investigating the freezing point depression of water. Historically, colligative properties have been one means. As a first step towards the greening of instructional laboratories, we present a new greener version of a laboratory procedure designed to measure colligative properties. Get a printable copy pdf file of the complete article 481k, or click on a page. These include, vapour pressure lowering, boiling point elevation, freezing point depression and osmotic pressure. In any equilibrium system, regardless of whether it is in a gravitational field or whether it contains walls, semipermeable membranes, phase transitions, or solutes, all. Both the boiling point elevation and the freezing point depression are proportional to the. The properties that exhibit such changes are called the colligative properties and include vaporpressure lowering. Freezingpoint depression to determine an unknown compound. Colligative properties freezingpoint depression and.
Colligative properties boiling point elevation and. The freezing point depression thus is called a colligative property. Colligative properties determination of the molar mass of a compound by freezing point depression. There are different types of colligative properties of a solution. Freezing point depression and boiling point elevation are examples of colligative properties. To complete this calculation, the mass of solute and solvent must be known as well as the freezing pointsboiling points of the pure solvent and the solution. Then, they solve several problems relating to freezing point depression.
Determination of molecular weight by freezing point depression or boiling point elevation 8. Colligative properties ch102 general chemistry, spring. Remember k is a constant for a given solvent and represents by how many degrees the freezing point will change when 1. Investigating freezing point depression and cirrus cloud. Colligative properties colligative properties of solutions are properties that depend upon the concentration of solute molecules or ions, but not upon the identity of the solute. Derivation of freezingpoint depression from chemical potential.
Different types of colligative properties of solution. Make ice cream in a baggie from anne marie helmenstine, ph. This experiment focuses on the property of freezingpoint depression. The effect of solute on a solvent due to the number of particles is called a colligative property. The vapor pressure of a pure liquid at a given temperature is a characteristic property of that liquid. Solutions 06 i colligative property depression in freezing point. These properties include boiling point elevation, freezing point depression, and osmotic pressure.
The depression in the freezing point of a pure substance when an impurity is added to it is a colligative property. Solution chemistry is an important topic in our understanding of general chemistry. The vapor pressure is the escaping tendency of solvent molecules. Similarly, antifreeze lowers the freezing point and lowers the boiling point. The freezing point depression is measured, and the freezing point depression constant, k f is known. The generally accepted view of osmotic pressure is that it is a colligative property, along with freezing point depression, boiling point. Colligative properties of simple solutions science. Freezing point depression and molecular weight page 2 of 9. The colligative property law describes these effects, stating that the freezing point and boiling point of a solution differ from those of the pure solvent by amounts that are directly proportional to the molal concentration of the solute brown, 203204. Freezingpoint depression is the decrease of the freezing point of a solvent on the addition of a. Design experiments to answer a research question about the influence adding a solute has to the solvents physical properties. The technique is insensitive and only useful for low molecular weight polymer e. When the vapor pressure of a solvent is equal to atmospheric pressure, the solvent boils.
Properties that depend on the concentration of particles molecules, ions, etc. Chemistry experiment 3 colligative properties freezing point depression. Colligative property an overview sciencedirect topics. Student exploration colligative properties answer key. Additionally, the concept of freezing point depression, a topic commonly encountered. Colligative properties by definition a colligative property is a solution property a property of mixtures for which it is the amount of solute dissolved in the solvent matters but the kind of. Examples of colligative properties are osmotic pressure see osmosis, lowering of vapour pressure, depression of freezing point, and elevation of boiling point. A greener approach for measuring colligative properties. T fp are the change in boiling point and freezing point respectively, k bp and k fp are the boiling and freezing constants for a particular solvent, and i is the vant hoff factor which is used to account for the number of particles a given. Factor which accounts for deviation of colligative property due to electrolytic nature of solute vant hoff factor i. Colligative properties such as freezing point depression or boiling point elevation can be used to calculate the molecular weight of a soluble solid. The colligative properties of solutions consist of freezing point depression, boiling point elevation, vapor pressure lowering and osmotic.
Learn vocabulary, terms, and more with flashcards, games, and other study tools. Boiling point elevation 6 freezing point depression 7. The freezing point of a substance is the temperature at which the solid and liquid forms can coexist indefinitely that is, they are in equilibrium. The colligative properties of a solution depend on only the total number of dissolved particles in solution, not on their chemical identity. Freezing point depression is a colligative property observed in solutions that results from the introduction of solute molecules to a solvent. Under these conditions molecules pass between the two phases at equal rates because their escaping tendencies from the two phases are identical. Colligative properties of solutions such as freezing point depression are. Freezingpoint depression and boilingpoint elevation. Determination of molar mass by freezing point depression using paradichlorobenzene introduction. Each mole of solute particles lowers the freezing point of 1 kilogram of water by 1. If the mass of solvent is known, the number of moles of solute may be calculated from the molality. A colligative property is one which depends upon the number of particles in solution without regard to their identity. The addition of a nonvolatile solute one without a measurable vapor pressure decreases the vapor pressure of.
Colligative collective properties of solutions they are properties whose values depend only on the number of solute particles per unit volume of solution and not on the type of solute, collective properties of solutions are vapour pressure depression, boiling point elevation and freezing point depression. Colligative properties and dissociation of electrolytes 9. Colligative properties are properties that depend only upon the number of solute atoms, ions, or molecules in a solution and not on the nature of those atoms, ions or molecules. Math handbook for a math refresher and practice, direct students to dimensional analysis, page r66. It means that irrespective of the nature of the impurity, solely. Colligative properties 1 colligative properties 2 colligative properties. The four colligative properties are freezingpoint depression, boilingpoint elevation, osmotic pressure, and vaporpressure lowering. Are properties that depend on the number of dissolved particles only. Freezing point depression e1 purpose the experiment to be performed is divided into three sections. Freezing point depression is one of the colligative properties of solutions discussed in this unit. Boiling point elevation and freezing point depression. Colligative properties of solutions presentation chemistry. For a given solutesolvent mass ratio, all colligative properties are inversely proportional to solute molar mass. This video lecture includes vapour pressure lowering boiling point elevation freezing point depression osmotic pressure and reverse osmosis.