Solutions Vocabulary and Concepts

Definitions Solution -Solution - a uniform, homogeneous mixture (on the molecular level) that may contain solids, liquids, or gases. Solvent Solvent – the substance that dissolves the solute; present in a greater amount than the solute. Solute Solute - substance being dissolved

 The solvent is usually in greater quantity and is of the same phase as the resulting solution.  The solute is usually in lesser quantity and may be a different phase than that of the solution.  Solid sugar (solute) is dissolved in liquid water (solvent) to make liquid lemonade (solution). How does one know which is the solute and which is the solvent?

Solution = Solute + Solvent Solute - gets dissolved Solvent- does the dissolving –A–Aqueous(water) –T–Tincture(alcohol) –A–Amalgam(mercury) –O–Organic(organic solvent) Polar Non-polar Dental filling

Example Types of Solutions SoluteSolventExample Gas Air ( oxygen in nitrogen) GasLiquidSeltzer (CO 2 in water) Liquid Antifreeze (ethylene glycol in water) SolidLiquidOcean water (salt in water) LiquidSolidDental filling (mercury in silver) Solid Sterling silver (copper in silver)

Types of Solutions Solid Solutions –Gold jewelry 14/18 carat– solution of gold and copper –Sterling silver – solution of silver and copper –Two metals in a solution are called ALLOYS

Gaseous Solutions –Two gases –Air – Mixture of mostly nitrogen and oxygen Types of Solutions

Liquid Solutions –Can involve a solid, gas, or liquid solute –Oxygen dissolves easily in water for fish to “breath” –Salts (solid) also dissolve easily in water (sea water) Types of Solutions

 Soluble: Describes a substance that can be dissolved in a given solvent.  Insoluble: Describes a substance that cannot be dissolved in a given solvent.  Miscible: Describes two liquids that are soluble in each other.  Immiscible: Describes two liquids that are not soluble in each other. More Definitions

 Suspension: A type of heterogeneous mixture that contains particles which settle out over time and can be separated from the mixture by filtration.  Colloids: Heterogeneous mixtures containing particles larger than the molecular species in solutions, but smaller than suspension particles. Typical particle sizes are between 1 and 100 nanometers in diameter.  Solubility: The maximum amount of solute that will dissolve in a given solvent at a specific temperature and pressure. Solubility is determined by the nature of the solute and solvent. Still More Definitions

Solubility Depends on Temperature

solutionscolloidssuspensions < 1 nm> 100 nm -single atoms -small molecules -ions -polyatomic ions -aggregates of atoms, molecules or ions -macromolecules (proteins) -clumps of particles, -mineral grains such as sand Comparison of Solutions, Colloids, and Suspensions

solutionscolloidssuspensions < 1 nm> 100 nm Light passage… Passage of lightScattering in beam Scattering in all directions

Centrifugation can be used to separate solids from liquids Spin the sample very rapidly: the denser materials go to bottom. Separate blood into serum and plasma –Serum (a clear solution) –Plasma (contains red blood cells) Blood RBC’s Serum A AFTER Before B C

 If the mixture contains solids and liquids such that the solids part of the mixture would float to the bottom naturally or go to the bottom by centrifugation, then it is a suspension. If not, go to the next step.  If the mixture is transparent (you can see through it), then the mixture is a solution. If not, go to the next step.  If the mixture is slightly hazy or is difficult to see through, it is a colloid. As a check, is it a mixture like milk that you cannot see through? Rules for Determining Solution, Colloid, or Suspension

Making solutions In order to dissolve, the solvent molecules must come in contact with the solute. Stirring moves fresh solvent next to the solute. The solvent touches the surface of the solute. Smaller pieces increase the amount of surface area of the solute.

Water Molecule How does the polarity of water aid the dissolution of solutes? O H H Hydrogen bond   What is a polar molecule?

Dissolution of Solid NaCl

 Solvation –  Solvation – t he process of surrounding solute particles with solvent particles to form a solution. solute particles are separated and pulled into solution solute particles are surrounded by solvent particles Solvation

Polar water molecules interact with positive and negative ions Animation

Dissolving of NaCl HH O Na Cl hydrated ions

Dissolving of Salt in Water NaCl(s) + H 2 O  Na + (aq) + Cl - (aq)

Dissolving process in water Na + Cl - 1. Overcome attractive forces in solid 2. Hydration of solute Orientation of water molecules around solute

How do I get sugar to dissolve faster in my iced tea? Stir, and stir, and stir Add sugar to warm tea then add ice Grind the sugar to a powder Fresh solvent contact and interaction with solute Greater surface area, more solute-solvent interaction Faster rate of dissolution at higher temperature