mixtures a combination of two or more pure substances in which each pure substance retains its own...
TRANSCRIPT
Mixtures
• A combination of two or more pure substances in which each pure substance retains its own individual chemical properties– physical combination– can be separated physically – has no definite ratio
SECTION 3.3 – Mixtures
Homogeneous Mixtures
• Mixture with a constant composition throughout– each and every part is identical– different part cannot typically be identified– also called a solution
• Also known as solutions, which can contain solids, liquids, or gases.
• A solid-solid solution known as steel is called an alloy, which is a mixture of metal & nonmetal.
SECTION 3.3 – Mixtures
Heterogeneous Mixtures
• Mixture that is not blended smoothly throughout.– each part is NOT identical– parts of mixture are typically easy to identify
SECTION 3.3 – Mixtures
Mixtures versus Compounds
S
Fe
Physically mixed, can be separated by physical means.
Chemically reacted, cannot be separated by physical means.
Separating Mixtures
• Filtration– uses a porous
barrier to separate a solid from a liquid
• Distillation– uses the
differences in boiling points
SECTION 3.3 – Mixtures
Using physical properties to separate mixtures
filtration distillation crystallizationfiltration distillation crystallizationsolubilitysolubility bp bp solubility solubility
Separating Mixtures
• Crystallization– results in the formation of pure
solid particles of a substance from a solution containing a dissolved substance
• Chromatography (1) (2)
– separates components of a mixture on the basis of the tendency of each to travel or be drawn across the surface of another material
SECTION 3.3 – Mixtures
Separating Mixtures
• Solubility– Water is added to the mixture and one part of the
mixture dissolves into the water and the remaining component can be filtered out.
– The water & substance solution must then go through distillation or crystallization to remove the dissolved substance from the water.
– SALT DISSOLVING IN WATER (1) (2)
• Magnetism– Process by which parts are separated out based on
their magnetic properties
SECTION 3.3 – Mixtures
Elements
• A pure substance that cannot be separated into simpler substances by physical or chemical means.– 91 occur naturally– Allotropes- element is found in more than one form.
• Ex. Carbon- diamond & graphite, Oxygen- O2 & O3.
– Diatomic elements- found as a pair with itself• Ex. O2, N2, F2, Cl2, H2, I2, Br2
– Expressed with a chemical symbol
-one, two or three letters
-only the first letter is capitalized
-organized on the Periodic Table
SECTION 3.4 – Elements & Compounds
Periodic TableHorizontal
rows-periodsVertical row-
groups/family– Elements in a
group/family together have similar properties
SECTION 3.4 – Elements & Compounds
Compounds
• Chemical combination of two or more elements– definite ratio– can only be separated by chemical changes– Compounds that occur naturally are more stable than
the individual component elements.– properties of a compound are different from the
properties of the elements that make itWater
aspirinsugarNaCl (salt)
NH3 (ammonia)HCl (hydrochloric acid)Fe2O3 (Iron III Oxide)
SECTION 3.4 – Elements & Compounds
Law of Definite Proportions
• A compound is always composed of the same elements in the same proportion by mass
• Percent mass of element
by Mass =
mass of compound X 100
SECTION 3.4 – Elements & Compounds
Energy
• The ability to do work or produce heat.
• Energy exists as 2 basic forms: potential energy & kinetic energy.– Potential energy- stored energy or energy due
to the composition or position of an object.– Kinetic energy- energy of motion.
• Work = Force x Distance
Conservation of Energy
• States that in any chemical reaction or physical process, energy can be converted from one form to another, but it is neither created nor destroyed. It can be accounted for as heat, stored energy, or work.
• Heat- energy transferred from an object at higher temperature to one at a lower temp.
• Temperature- measure of the average kinetic energy of the particles in a system.