3-1 Everyday Changes In Substances

Everyday Changes in Chapter 3

Understanding Solutions Chapter 3, Sections 1

Solutions and Suspensions  Suspension- a mixture in which particles can be seen and easily separated by settling or filtration  Not evenly mixed  Pepper & water

 Solution- a well-mixed mixture; has the same properties throughout  Particles of a solution are too small to see

Solvents and Solutes Solvent

Solute

 Solvent- part of a solution present in the largest amount

 Solute- substance that is present in a solution in a smaller amount and dissolved by the solvent

 Water is commonly a solvent; “universal solvent”

Particles in a Solution  Whenever a solution forms, particles of the solute change physically. They leave each other and become surrounded by particles of the solvent.

Particles in a Solution Ionic Solids in Water

Molecular Solids in Solutions and Water Conductivity

oNot all substances break into ions when dissolved in water oSugar breaks into neutral molecules oPolar water molecules  Water molecules surround each ion as it attract the polar sugar leaves the surface of molecules the crystal. oCovalent bond are undisturbed  When ionic solids mix with water, the positive and negative ions are attracted to polar water molecules

 Ionic compounds dissolved in water conduct electricity, but molecular compounds do not  Electricity does not flow if there are no ions present

 Dilute solution- a little solute is dissolved in the water

 Concentrated solution- more solute dissolved in the water

Concentration

Solubility  Solubility is a measure of how well a solute can dissolve in a solvent at a given temperature  Saturated solution- no more solute will dissolve in the solvent  Unsaturated solution- more solute can be dissolved in the solvent  Solubility is a physical property of matter

Changing Solubility Temperature

Solvents

 Unlike solids, gases become less soluble when the temperature goes up (soda)

 Solvents effect how well solutes dissolve

 Many solids dissolve better when the temperature of the solvent increases (sugar)

 Ionic and polar compounds dissolve in polar solvents (water-based paint)  Non-polar compounds do not dissolve in polar solvents (oil-based paint)

Effects of Solutes on Solutions Lower Freezing Points

Higher Boiling Points

 Solutes lower the freezing point of a solvent

 Solutes raise the boiling point of a solvent

 Solute particles make it harder for water molecules to form crystals and freeze

 In a liquid molecules are moving close to each other.

 Homemade ice cream; icy roads

 In a gas, molecules are far apart and moving rapidly  Presence of salt makes boiling point of water higher