1. Solutes and Solubility

2. Link to a set of 9 quick lessons about solutes and solubility:

3. Classification of Matter
Classify according to 4 states of matter
Classify by the units they are made of

4. Elements Matter is made up of atoms
if all atoms in a sample have same identity, that matter is an element.

5. Examples Al Cu Ag

6. Compounds
Made from atoms of 2 or more elements that are combined chemically (atoms are bonded together)

7. H2 + O (hydrogen and oxygen)
Makes H2O (water)

8. Na + Cl (sodium and chlorine)
NaCl salt

9. Molecules
Made of 2 or more atoms that are combined chemically (atoms are bonded together)
The atoms can be the same or different elements

10. Molecules Compounds are always molecules
Elements may be individual atoms or they can be molecules
H2, O2, N2 are all diatomic elements
S8 is a molecule of 8 sulfur atoms

11. Chemical Formulas C6H12O6 is the formula for glucose
Use symbols and numbers to represent the elements found in a substance and the number of each of those elements present in the substance
C6H12O6 is the formula for glucose

12. Wrap-up Substance: an element or compound
can’t be reduced to more basic components by physical processes

13. Mixtures
Material made up of 2 or more substances that can be separated by physical means.
Each substance in a mixture keeps its own properties and identity

14. Salt water
NaCl H2O

15. Mixtures cont’d
Don’t always contain the same amounts of the different substances that make them up

16. Heterogeneous mixture
Different materials can be easily distinguished
Not uniformly mixed

17. Examples
Granite
Concrete
Inside of your locker or backpack

18. Solutions Homogeneous mixture
Two or more substances are uniformly mixed together

19. Solution particles never settle to bottom of container
Remain constantly and uniformly mixed

20. Types of solutions
Solutions are classified as solid, liquid, or gas depending on their final state

21. Solution terms
Solute: substance being dissolved, less than 50% of a solution
Solvent: substance dissolving the solute, present in largest amount

22. Air: 78% N, 21% O, 1% Ar
Solvent of air?
Sterling silver: 92.5% Ag, 7.5% Cu. Solvent?

23. Alloy – a solution of a metal and another element (usually another metal)
Ex.: brass (copper and zinc); bronze (copper and tin); cast iron (iron and carbon)

24. Solids dissolving in liquids
Dissolving of a solid in a liquid occurs at the surface of the solid
Solutes dissolve from the outside to the center

25. The more surface there is, the faster something dissolves
A large block has less surface available (less surface area) than the same block broken into pieces

26. As large blocks are broken down into smaller pieces, the total surface area increases.

27. Animations of salt dissolving in water
animation of salt dissolving in water
another animation of salt dissolving in water

28. Rate of Dissolving
Rate of solubility depends on how the solute is dissolved
grams of solute/min

29. Stirring speeds up dissolving –brings more fresh solvent into contact with more solute, also moves solute particles around in the solvent
Stirring adds kinetic energy to a solution and helps solvent and solute particles collide

30. Grinding a solute speeds dissolving of solid in liquid - large crystals become small ones and solvent has more surface area to work on

31. Increasing the temperature of solvent increases rate at which most solids dissolve - increasing temp speeds up action of molecules of the solvent and the solute

32. Solubility
Physical property of matter that relates to the ability of a solute to dissolve in a solvent
A measure of how easily or how quickly a solute dissolves in a solvent

33. Physical properties: Rate of Solubility
Rate of solubility = mass of solute dissolved/time to dissolve
To calculate the rate of solubility divide the mass of the solute by the time it takes to dissolve
Rate of solubility units: g/min or g/sec

34. Physical properties: Rate of Solubility
Rate of solubility is affected by temperature and stirring
Rate of solubility is a property of a substance
There are tables of solubility rates for various substances

35. Miscibility
A measure of how easily or how quickly a liquid solute dissolves in a liquid solvent
Water and oil are immiscible (they don’t dissolve in each other)

36. Concentration
A measure of the amount of one substance in a specific volume of another substance.
Concentration units: g/mL
Ex. Grams of solute per mL of solvent

37. Concentration
A solution that has 20 g of solute dissolved in 100 mL of solvent is more concentrated than a solution that has 8 g of solute dissolved in 100 mL of solvent

38. Types of solutions based on amt. of solute dissolved
Saturated solution - solution that has dissolved all the solute it normally can hold at a given temperature

39. If you heat the mixture to a higher temp, more solute can dissolve - as temp. increases, amt. of solute that can dissolve increases

40. Unsaturated solution - any solution that can dissolve more solute at a given temp.
Each time a saturated solution is heated to a higher temp, it may become unsaturated

41. NaCl(s) <==> Na+(aq) + Cl-(aq)
Saturation point is 36g/100mL or 0.36g/mL

42. Supersaturated solution - contains more solute than a saturated one has at that temperature

43. This kind of solution is unstable - when a small crystal of the solute is added to a supersaturated solution, excess solute quickly crystallizes out

44. Saturation point
Point where no more solute will dissolve in a solution
A concentration above which the solute will no longer dissolve in the solvent, the solution is saturated and can’t take any more

45. Summary Add a solute crystal to solution:
If crystal dissolves, solution is unsaturated
If crystal doesn’t dissolve, solution is saturated (crystal just sinks to the bottom of the container)
If additional solute comes out, solution is supersaturated