Chapter 18: How Chemicals Mix BIG IDEA: Most everything is a mixture
Dec 18, 2015
18.1 Most Materials are Mixtures
Mixture- a combination of 2 or more substances in which each substance retains its own properties.
-Each substance in a mixture maintains its chemical identity
The components of mixtures can be separated from one another by using differences in their physical properties.-Differences in: state of matter, density, boiling/melting points
Ex: filtration: separating a solid/liquid mixture via filter paperEx: distillation: separating a solid/liquid mixture via heating
18.2 Chemist’s Classification of MatterPure materials consist of a single element or compoundImpure materials are a mixture of 2+ elements or compounds
Classification of mixtures: Heterogeneous vs. Homogenous- Uneven composition throughout- Even composition throughout
Homogenous mixtures can be solutions or suspensions
Solution: All components are in the same phase
Suspension: Different components are in different phases
-The easiest way to tell the 2 apart is to spin in centrifuge
18.3 Making SolutionsSolutions aren’t always liquids (gemstones=solid, air=gas)
In solutions the component present in the largest amount is the solvent, all other components are solutes.
Ex: Salt water. Water= solvent b/c substance is dissolved in itSalt= Solute, it’s the component being dissolved
There is a limit to how much of a solute can be dissolved.
-In saturated solutions no more solute can be dissolved-Unsaturated solutions have not yet reached their dissolving limit
Identify solvent vs. solute
Which is solvent, which is solute?
Salt water
Air (A solution of 78% N2, 21%O2 and various other gases)
Bronze (95% Cu, 5% Sn)
Kool-Aid
18.4 Concentration and the Mole
Concentration=
- Something that is less concentrated is more watered down
A mole of any type of particles = 6.02 ∙1023
molecules
Avogadro's number
Another common unit of concentration used by chemists:
Molarity=
1 molar solution= 1M= 1 mole/L solution
- Higher molarity=higher saturation=
higher concentration.
18.5 Solubility
Solubility= ability of a solute to dissolve in a solvent.Can dissolve= solubleCan NOT dissolve= insoluble
-Solubility depends on the microscopic attractions between solute particles and solvent particles
Solubility increases w/:
Increased temperatures(More kinetic energy, particle movement increases)
Broken into smaller pieces or being stirred. (More surface area [amount of space something takes up] comes into contact w/ the solvent
18.6 Soaps and DetergentsSoap works b/c it has both nonpolar and polar properties
_Polar heads are attracted to nonpolar grime. The nonpolar tails are attracted to water, so this allows the soap + water to flow and get the grime off.
Detergents=stronger grease penetration
Purifying the Water we DrinkWe purify water by taking advantage of the differences in physical properties of water and the solutes/particles it contains
1.Take groundwater/ lake/river water and remove pathogens by mixing w/ chemicals.
2.The impurities clump together and settle @ bottom
3.Water is filtered
People also make drinking water by boiling the source water