1. Chapter 18: How Chemicals Mix
BIG IDEA: Most everything is a mixture

2. 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
Most materials we encounter are mixtures, of elements, compounds, or of elements with compounds. Our atmosphere is a mixture of N,O, Ar, CO2, H2O. Tap water also has other cmpnds such as: Ca, Mg, Cl, F, Fe, K which helps to destroy bacteria and promote health. Since substances in a mixture maintain their identity it is a PHYSICAL change (easy to reverse)

3. 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 paper
Ex: distillation: separating a solid/liquid mixture via heating
Ex of filtration: how coffee is made, separating salt water. Distillation, separating salt water

4. 18.2 Chemist’s Classification of Matter
Pure materials consist of a single element or compound
Impure materials are a mixture of 2+ elements or compounds
Classification of mixtures: Heterogeneous vs. Homogenous
Uneven composition throughout
Even composition throughout

6. 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
Solution: all solid/liquid or gas, no combo. Components of a solution are no so readily distinguished.
Centrifuges separates the components of suspensions, but not solutions

7. 18.3 Making Solutions
Solutions 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 it
Salt= Solute, it’s the component being dissolved

8. 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
In saturated solutions the solute can no longer be mixed evenly, and the components of a mixture take on different phases of matter

9. 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

10. 18.4 Concentration and the Mole
Something that is less concentrated is more watered down
A mole of any type of particles = 6.02 ∙1023 molecules
Avogadro's number
A mole is like inferring that a couple=2, a dozen=12. A mole is a very large number, but they are used in chemistry b/c molecules are so small. Number of grams in a solution tells you the mass of a solute in a given solution, whereas the number of moles in a given solution actually tells you how many molecules are in a solution. Avogadro’s number is named after the Italian scientists Amedeo Avagadro, who proposed that the volume of a gas is proportional to the number of atoms of molecules of that gas

11. Molarity= # 𝑚𝑜𝑙𝑒𝑠 𝑜𝑓 𝑠𝑜𝑙𝑢𝑡𝑒 𝐿 𝑜𝑓 𝑠𝑜𝑙𝑢𝑡𝑖𝑜𝑛
Another common unit of concentration used by chemists:
Molarity= # 𝑚𝑜𝑙𝑒𝑠 𝑜𝑓 𝑠𝑜𝑙𝑢𝑡𝑒 𝐿 𝑜𝑓 𝑠𝑜𝑙𝑢𝑡𝑖𝑜𝑛
1 molar solution= 1M= 1 mole/L solution
- Higher molarity=higher saturation= higher concentration.
Molarity tells us how saturated a solution is. Higher molarity=higher saturation= higher concentration. When working with dangerous chemicals it is very important to know the concentration of a substance

12. 18.5 Solubility
Solubility= ability of a solute to dissolve in a solvent.
Can dissolve= soluble
Can NOT dissolve= insoluble
-Solubility depends on the microscopic attractions between solute particles and solvent particles
Do you think that substances w/ great attractive forces dissolve more or less easily? (more!)

13. 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

14. 18.6 Soaps and Detergents
Soap 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

16. Purifying the Water we Drink
We purify water by taking advantage of the differences in physical properties of water and the solutes/particles it contains
Take groundwater/ lake/river water and remove pathogens by mixing w/ chemicals.
The impurities clump together and bottom
Water is filtered
People also make drinking water by boiling the source water