What are colligative properties give examples

\( \newcommand\) No headers Colligative properties are the physical changes that result from adding solute to a solvent. Colligative Properties depend on how many solute particles are present as well as the solvent amount, but they do NOT depend on the type of solute particles, although do depend on the type of solvent. • Anomalous Colligative Properties (Real Solutions) Anomalous colligative properties are colligative properties that deviate from the ideal colligative behavior. It is quantified by the introduction of the Van't Hoff factor. • Boiling Point Elevation The boiling points of solutions are higher than that of the pure solvent. This effect is directly proportional to the molality of the solute. • Freezing Point Depression The freezing points of solutions are all lower than that of the pure solvent. The freezing point depression is directly proportional to the molality of the solute. • Osmotic Pressure The osmotic pressure of a solution is the pressure difference needed to stop the flow of solvent across a semipermeable membrane. The osmotic pressure of a solution is proportional to the molar concentration of the solute particles in solution. • Vapor Pressure Lowering The vapor pressure of a solvent in a solution is always lower than the vapor pressure of the pure solvent. The vapor pressure lowering is directly proportional to the mole fraction of the solute.

• Name the four colligative properties. • Calculate changes in vapour pressure, melting point, and boiling point of solutions. • Calculate the osmotic pressure of solutions. The properties of solutions are very similar to the properties of their respective pure solvents. This makes sense because the majority of the solution is the solvent. However, some of the properties of solutions differ from pure solvents in measurable and predictable ways. The differences are proportional to the fraction that the solute particles occupy in the solution. These properties are called colligative properties; the word colligative comes from the Greek word meaning “related to the number,” implying that these properties are related to the number of solute particles, not their identities. Before we introduce the first colligative property, we need to introduce a new concentration unit. The mole fraction of the ith component in a solution, χ i, is the number of moles of that component divided by the total number of moles in the sample: (χ is the lowercase Greek letter chi.) The mole fraction is always a number between 0 and 1 (inclusive) and has no units; it is just a number. A solution is made by mixing 12.0 g of C 10H 8 in 45.0 g of C 6H 6. What is the mole fraction of C 10H 8 in the solution? Solution We need to determine the number of moles of each substance, add them together to get the total number of moles, and then divide to determine the mole fraction of C 10H 8. The number of moles o...

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%2FFreezing_Point_Depression \( \newcommand\) is the freezing point depression, \(T_f\) (solution) is the freezing point of the solution, \(T_f\) (solvent) is the freezing point of the solvent, \(K_f\) is the freezing point depression constant, and m is the molality. Introduction Nonelectrolytes are substances with no ions, only molecules. Adding solutes to an ideal solution results in a positive \(ΔS\), an increase in entropy. Because of this, the newly altered solution's chemical and physical properties will also change. The properties that undergo changes due to the addition of solutes to a solvent are known as The freezing point and boiling point of a pure solvent can be changed when added to a solution. When this occurs, the freezing point of the pure solvent may become lower, and the boiling point may become higher. The extent to which these changes occur can be found using the formulas: \[\Delta_b = K_b \times m\] where \(m\) is the solute molality and \(K\) values are proportionality constants; (\(K_f\) and \(K_b\) for freezing and boiling, respectively). Molality Molality is defined as the number of moles of solute per kilogram solvent. Be careful not to use the mass of the ...

• Chemistry • Physical Chemistry • Colligative Properties Colligative Properties Have you ever wondered what happens when we add salt to water when cooking pasta? In addition to giving it flavor, salt increases the boiling point of the solution, allowing you to cook your spaghetti faster in salt water! Boiling point elevation is a colligative property. So, without further ado, let's dive into the colligative properties of solutions! To start, let's look at… Colligative Properties • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Have you ever wondered what happens when we add salt to water when cooking pasta? In addition to giving it flavor, salt increases the boiling poin...

This year in the midwest United States, winter has been a fickle friend. I haven’t seen the same amount of snow or ice as in recent years, but I still made sure I was prepared for it at our home. I went to my local big box hardware store in December and contemplated buying rock salt (NaCl), and NaCl/calcium chloride mixture, or just calcium chloride. Growing up my dad had switched entirely to calcium chloride because it was less damaging to the brick pavers leading to our porch and backyard. In fact, calcium chloride is generally much safer toward plants and soil than NaCl. Even though calcium chloride is much more expensive than rock salt (it was about twice the cost for 10 pounds more), that what’s I chose. Why? Because I am a chemist by trade (and chemistry teacher). I actually considered the colligative properties of calcium chloride and knew that it would lower the freezing point of water much more than NaCl. Considering the qualitative aspects of colligative properties, the more ions that the formula can be broken down into, the greater the effect. NaCl consists of 2 different ions (Na + and Cl - ) while calcium chloride, CaCl 2 , consists of 3 ions (Ca +2 and 2 Cl - ). Quantitatively, we would discuss the van’t Hoff factor and use molality calculations to determine how much the temperature increases or decreases. So why bring up colligative properties? About 4 years ago I was teaching AP Chemistry at a parochial high school in Indianapolis, IN. I went to an AP Chemi...

Automotive antifreeze, kidney dialysis and using rock salt to make ice cream don’t seem like they would have anything in common. But they all depend upon the colligative properties of solutions. These properties are the physical properties of solutions that depend only on the ratio of the number of particles of solute and solvent (e.g., salt in water) in solution and not on the identity of the solute. TL;DR (Too Long; Didn't Read) Too Long;Didn't Read (TL;DR) There are four colligative properties: vapor pressure, boiling point, freezing point and osmotic pressure. These physical properties of solutions depend only on the ratio of the number of particles of solute and solvent in solution and not on what the solute is. Decreasing the Vapor Pressure by Adding a Solute At equilibrium, the gas phase (such as water vapor) above the solvent has a partial pressure equal to p1. Adding a solute (like table salt, NaCl), decreases the partial pressure of the solvent in the gas phase. The decrease in vapor pressure is caused by the solvent molecules on the surface of the solution being replaced by solute molecules. The solvent molecules “crowd out” vaporization. Because there are less solvent molecules on the surface, the vapor pressure decreases. Boiling Point Elevation in a Mixture Bringing a solvent to a boil essentially vaporizes the solvent. Boiling point elevation, or increasing the temperature at which the solvent boils, occurs for a similar reason as vapor pressure depression. ...

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