LOGO Course lecturer : Jasmin Šutković 25 th April 2016 Chemistry - SPRING 2016 Lecture 8: Solutions

Contents International University of Sarajevo 1.Solutions 2.Electrolytes and Non-electrolytes 3.Solubility 4.Concentrations of Solutions 5.Dilution of Solutions 6.Properties of Solutions 7.Osmosis

Introduction to Solution  Solutions are everywhere around us. Most of the gases, liquids, and solids we see are mixtures of at least one substance dissolved in another. There are different types of solutions.  The air we breathe is a solution that is primarily oxygen and nitrogen gases. Carbon dioxide gas dissolved in water makes carbonated drinks. When we make solutions of coffee or tea, we use hot water to dissolve substances from coffee beans or tea leaves.

 Solutions can be described by their concentration, which is the amount of solute in a specific amount of that solution.  These relationships, which include mass, volume, and molarity can be used to convert between the amount of a solute and the quantity of its solution.  Solutions are also diluted by adding a specific amount of solvent to a solution. Introduction to Solution

Solutions  A solution is a homogeneous mixture in which one substance, called the solute, is uniformly dispersed in another substance called the solvent.

Types of Solutes and Solvents  Solutes and solvents may be solids, liquids, or gases

Solvent - Water

Water in our body  Every day you lose between 1500 and 3000 mL of water from the kidneys as urine, from the skin as perspiration, from the lungs as you exhale, and from the gastrointestinal tract

Formation of Solutions  Energy is needed to start the interaction of solutes and solutions.  Attraction must occur and it will happen if solution and solutes have similar polarity!  The expression “like dissolves like” is a way of saying that the polarities of a solute and a solvent must be similar in order for a solution to form.

Like dissolves like

Solutions with Nonpolar Solutes  Compounds containing nonpolar molecules, such as iodine I2, oil, or grease, do not dissolve in water because there are essentially no attractions between the particles of a nonpolar solute and the polar solvent.  Nonpolar solutes require nonpolar solvents for a solution to form.

Electrolytes and Nonelectrolytes  Solutes can be classified by their ability to conduct an electrical current.  When electrolytes dissolve in water, the process of dissociation separates them into ions forming solutions that conduct electricity.  When nonelectrolytes dissolve in water, they do not separate into ions and their solutions do not conduct electricity.

Types of Electrolytes  Strong electrolytes - 100% dissociation of the solute into ions. Exp: Mg(NO3)2  Weak electrolytes- partial dissociation of the solutes into ions.Exp : HF

Electrolytes in the body play an important role in maintaining the proper function of the cells and organs in the body. Typically, the electrolytes sodium, potassium, chloride, and bicarbonate are measured in a blood Test.

Solubility  The term solubility is used to describe the amount of a solute that can dissolve in a given amount of solvent.  Many factors, such as the type of solute, the type of solvent, and the temperature, affect the solubility of a solute.  Solubility, usually expressed in grams of solute in 100 g of solvent, is the maximum amount of solute that can be dissolved at a certain temperature.

Types of solutions  If a solute readily dissolves when added to the solvent, the solution does not contain the maximum amount of solute. We call this solution an unsaturated solution.  A solution that contains all the solute that can dissolve is a saturated solution.  When a solution is saturated, the rate at which the solute dissolves becomes equal to the rate at which solid forms, a process known as recrystallization.

Saturation problems High level of Uric acid High level of Calcium

Concentration of Solutions  The amount of solute dissolved in a certain amount of solution is called the concentration of the solution.  The amount of a solute may be expressed in units of grams, milliliters, or moles. The amount of a solution may be expressed in units of grams, milliliters, or liters. c= n/V

Mass percentage

Volume percent

Molarity of Solutions

Conversion factors

Dilution of Solutions  In chemistry and biology, we often prepare diluted solutions from more concentrated solutions.  In a process called dilution, a solvent, usually water, is added to a solution, which increases the volume.

Equation

Types of mixtures

Properties of mixtures

Osmosis – Osmotic pressure  The movement of water into and out of the cells of plants as well as the cells of our bodies is an important biological process that also depends on the solute concentration.  In a process called osmosis, water molecules move through a semipermeable membrane from the solution with the lower concentration of solute into a solution with the higher solute concentration.

Hemodialysis  If the kidneys fail to dialyze waste products, increased levels of urea can become life-threatening in a relatively short time. A person with kidney failure must use an artificial kidney, which cleanses the blood by hemodialysis.