AQUEOUS SYSTEMS
is a homogeneous mixture . An aqueous solution is water that contains dissolved substances. A aqueous solution is a homogeneous mixture . koolaid tea
A solution consists of two parts: solvent solute Solute --- sugar The particles being dissolved Solvent --- water The dissolving medium
Solute particles can be atoms, ions, or molecules, and their average diameters are usually less than 1 nm (10-9 m). Both solvent and solute pass through filter paper.
RULE: Like dissolves like. Substances that dissolve most readily in water include ionic compounds and polar covalent compounds. Water is a polar compound, and it will dissolve other polar compounds. Nonpolar compounds, such as oil, will not dissolve in water. Nonpolar substance like gasoline will dissolve in oil. RULE: Like dissolves like. Polar will dissolve polar. Nonpolar will dissolve nonpolar.
A substance that dissolves in a solvent is said to be soluble in that solvent. Sugar is soluble in water. A substance that does not dissolves in a solvent is said to be insoluble in that solvent. Oil is insoluble in vinegar.
How does a solute dissolve in a solvent? https://www.youtube.com/watch?v=0cPFx0wFuVs Time 1:30
O How does a solute like NaCl dissolve in a solvent? δ- H H δ+ δ+ Solvent - - water Solute - - NaCl δ- O H H δ+ δ+ https://www.youtube.com/watch?v=EBfGcTAJF4o
How does a solute dissolve in a solvent?
How does a solute dissolve in a solvent? Solvated Ions Ionic compound
The process of surrounding solute particles with To form a solution, solute particles must separate from one another and the solute and solvent particles must mix. Attractive forces exist between particles of all substances. Attractive forces exist between the pure solute particles, between the pure solvent particles, and between the solute and solvent particles. When a solid solute (NaCl) is placed in a solvent (water), the solvent particles completely surround the surface of the solid solute. Water particles collide with the surface of NaCl. The charged ends of the water molecules attract the positive sodium ions and negative chloride ions. If the attractive forces between the polar water molecules and ions are greater than the attractive forces holding the ions in the crystal, then the ions break away from the crystal. The water molecules surround the ions and the solvated ions move into solution. The process of surrounding solute particles with solvent particles to form a solution is called solvation.
Are all ionic compounds soluble in water? Barium sulfate (BaSO4) and calcium carbonate (CaCO3) are ionic compounds that are insoluble in water.
Why are some ionic compounds insoluble in water? In some ionic compounds, the attractions among the ions in the crystals are stronger than the attractions exerted by water. These compounds cannot be solvated and are therefore insoluble. AgCl is insoluble, forms white precipitate
Water is a good solvent for many molecular compounds. The O-H bonds in sucrose make the molecule polar.
When water is added to sucrose, each O-H bond becomes a site for hydrogen bonding with water. The attractive forces among sucrose molecules are overcome by the attractive forces between polar water molecules and polar sucrose molecules. Sucrose molecules leave the crystal and become solvated by water molecules.
Both oil and gasoline are nonpolar substances Both oil and gasoline are nonpolar substances. The attractive forces that hold molecules in oil together are similar in magnitude to the attractive forces that hold molecules in gasoline together. Molecules in oil can easily separate and replace molecules in gasoline to form a solution. Vegetable oil
Why doesn’t oil dissolve in water? Nonpolar will not dissolve in polar. Why? There are weak intermolecular forces between nonpolar molecules of oil. There are strong intermolecular forces (hydrogen bonds) between molecules of water. The intermolecular forces in oil are to weak to break apart the hydrogen bonds between water molecules, therefore oil cannot mix or dissolve in water.
SUSPENSIONS A solution A suspension is not a solution. Why do the particles remain suspended? Why do the particles settle? A solution A suspension is not a solution. A solution is a homogenous mixture composed of small particles that remain suspended. A suspension is a heterogenous mixture composed of large particles that settle out upon standing. The particles have a diameter of 1 nm or less. The particles have a diameter of 1000 nm.
Solution Suspension Particles are small and pass through filter paper. Particles are large and do not pass through filter paper.
SUSPENSIONS Sand and water flour and water
COLLOIDS A colloid is a heterogeneous mixture containing midsize particles that range in size from 1 nm to 1000 nm. The particles are spread, or dispersed, throughout the medium. Colloids have particles smaller than those in suspensions and larger than those in solutions. Particle size between 1 nm & 1000 nm Particle size < 1 nm Particle size > 1000 nm Solution Colloid Suspension
COLLOIDS Marshmallow Milk Whipped cream Aerosol Mayonnaise
COLLOIDS Jelly Gelatin Egg white Paint Starch in water Blood
Fog Dust in Air
The path of light is visible when the light is scattered by particles.
Fog and dust in air scatter light.
A beam of light is visible only when it is scattered by particles. In a solution, the particles are too small to scatter light. The particles in colloids and suspensions scatter light. The scattering of light by colloidal particles is called the Tyndall effect.