section 2, unit 2

Section 2, Unit 2

Mixtures and Separation Techniques

Separating These Mixtures

– Separation Techniques target the components’ differences in physical properties.• Review: What are Physical Properties?

• Filtration-• Evaporation-• Chromatography-• Electrophoresis-• Distillation-• Centrifugation –

Pure or Impure

• Chemists Classify Matter As Pure or Impure– Pure – If the material consists of only a single

element or a single compound– Impure – If the mixture contains two or more

elements or compounds

Pure or Impure

• Flow Chart

Pure or Impure

• Mixtures can be either

Homogeneous

or

Heterogeneous

Heterogeneous Mixture• Heterogeneous Mixture – The different components

can be seen as individual substances

Examples–“Snow” in a snow globe–Pizza–Pulp in Orange Juice

–Any Others??

Homogeneous Mixture• Homogeneous Mixture – Has the same composition

throughout. You can take multiple samples from different locations and the compositions will be the exact same.

Examples:• Air• Seawater• Kool-Aid

Solutions vs. Suspensions

– Homogeneous Mixtures can be either a Solution or a Suspension

• A Solution is when all components are in the same phase» Examples

• Atmosphere is ALL gaseous • Saltwater is ALL in solution (the NaCl is dissolved in the water)

• A Suspension is a Homogeneous Mixture where some components are in different phases

» Examples• Milk (proteins are suspended in solution)• Blood (cells and proteins are suspended in solution)• Clouds (tiny water droplets suspended in the atmosphere)

Separation• How can you separate these solutions??

– Milk (proteins are suspended in solution)– Blood (cells and proteins are suspended in solution)

– ___________________ » Yields two layers (solution on top, suspensions on

bottom)

Density

• Review:

– Mass- How much matter is contained in an object

– Volume- How much space an object takes up

– Density- ??

Density Derivation

• If density is the amount of matter per unit of volume, then what is the equation to calculate density?

• Equation __________________________

• How much space will a 54.8 g sample of Fe occupy if the density is 7.86 g/mL

– Note: g/mL = g/cm3 = g*mL-1 = g*cm3-1

Graphical Analysis

• Volume on the x-axis, Mass on the y-axis

• As the volume increases for a given substance, so does the mass, at a constant rate.

• The slope of this line is the DENSITY!!

• We can determine the identity of an unknown substance using its density.

Atoms are the Fundamental Components of Elements

– The Periodic Table contains a relatively small number of atoms that form an unlimited number of different materials.• This is based on how they combine or bond together

Atoms are the Fundamental Components of Elements

– The Periodic Table contains a relatively small number of atoms that form an unlimited number of different materials.• This is based on how they combine or bond together

– Element – Any material consisting of only one type of atom.– Atom – Submicroscopic particles in a sample. Each element

is designated by a symbol (Atomic Symbol)• Co =/= CO, only the first letter is capital

Atoms are the Fundamental Components of Elements

– Elemental Formula – How many atoms are bonded together in an element • Au = Gold ii. N2 = Nitrogen iii. Ni = Nickel

– Seven Diatomic Elements: –Oxygen, Hydrogen, Nitrogen, Bromine,

Chlorine, Iodine, Fluorine– How about diatomic oxygen vs. ozone, O3?

–Are they the same?–No, BUT both are elemental forms of oxygen

Combining Elements to Form Compounds

– Molecule- Consists of two or more atoms combined in a definite ratio

– Compound– Atoms of different elements bound to one another

– We had an Elemental Formula for elements, how will we represent chemicals bound together to form chemical compounds?

Combining Elements to Form Compounds

– We had an Elemental Formula for elements, how will we represent chemicals bound together to form chemical compounds?

– Chemical Formula – How much of what is in the compound (symbols and subscripts)• NaCl: One sodium per chlorine atom• MgCl2: One magnesium per two chlorine atoms

Combining Elements to Form Compounds

– Hydrogen Sulfide is one of the smelliest compounds. Rotten eggs get their characteristic bad smell from the hydrogen sulfide that they release. Can you infer from this information that elemental sulfur is just as smelly?

– *Compounds have Physical and Chemical properties that are different from the

properties of their elemental compounds

• Vocab sheet due Wednesday

• “Separation Techniques” lab tomorrow – dress appropriately.

• Periodic Table Quiz #2 coming up!!