1. Mixtures (Solutions) Ms. Rosendo

2. characteristics of these
Mixtures
a combination of two or more substances that do not combine chemically, but remain the same individual substances; can be separated by physical means
Two types:
Heterogeneous
Homogeneous
Based on the prefixes
“hetero” and “homo,”
what do you think are
characteristics of these
two types of mixtures?

3. Heterogeneous Mixture
“Hetero” means different
consists of visibly different substances or phases (solid, liquid, gas)
a suspension is a special type of heterogeneous mixture of larger particles that eventually settle
Example:
Notice the
visibly
different
substances
Trail Mix

4. Homogeneous Mixture “Homo” means the same
has the same uniform appearance and composition throughout; maintain one phase (solid, liquid, gas)
Commonly referred to as solutions
Example:
Notice the
uniform
appearance
Salt Water

5. Solution
a mixture of two or more substances that is identical throughout
can be physically separated
composed of solutes and solvents
Salt water is considered a solution. How
can it be
physically separated?
the substance in the smallest
amount and the one that dissolves in the solvent
the substance in the larger
amount that dissolves the solute
Iced Tea Mix
(solute)
Water
(solvent)
Iced Tea
(solution)
Colloids (milk, fog, jello) are considered solutions

6. Concentration
the amount of solute dissolved in a solvent at a given temperature
described as dilute if it has
a low concentration of
solute
described as saturated if it
has a high concentration of
described as supersaturated if
contains more dissolved solute
than normally possible

7. Solubility
the amount of solute that dissolves in a certain amount of a solvent at a given temperature and pressure to produce a saturated solution
influenced by:
What do we call things that are not soluble?
Temperature
Pressure
Solids increased temperature causes
them to be more soluble and vice versa
Gases increased temperature causes
them to be less soluble and vice versa
Ex. Iced Coffee
Solids increased pressure has no
effect on solubility
Gases increased pressure causes them
to be more soluble and vice versa
Ex. Soda, “The Bends”

8. Concentration of Solute
The amount of solute in a solution is given by its concentration.
Molarity ( M ) =
moles solute
liters of solution

9. PROBLEM: Dissolve 5.00 g of NiCl2 in enough water to make 250 mL of solution. Calculate the Molarity.
Step 1: Calculate moles of NiCl2
Step 2: Calculate Molarity
[NiCl2] = M

10. moles = M•V USING MOLARITY Step 1: Change mL to L.
What mass of oxalic acid, H2C2O4, is
required to make 250. mL of a M
solution?
moles = M•V
Step 1: Change mL to L.
250 mL * 1L/1000mL = L
Step 2: Calculate.
Moles = ( mol/L) (0.250 L) = moles
Step 3: Convert moles to grams.
( mol)(90.00 g/mol) = g

11. Learning Check
How many grams of NaOH are required to prepare 400. mL of 3.0 M NaOH solution?
1) 12 g
2) 48 g
3) 300 g

12. Two Other Concentration Units
MOLALITY, m
m of solution =
mol solute
kilograms solvent
% by mass
grams solute
grams solution
% by mass =

13. Calculating Concentrations
Dissolve 62.1 g (1.00 mol) of ethylene glycol in 250. g of H2O. Calculate molality and % by mass of ethylene glycol.

14. pH Scale
ranges from 0-14
Acids  found between a number close to 0 & 7
Bases  found between 7 & 14
Neutral  7
measures the acidity or basicity of a solution by focusing on the concentration of hydrogen ions (H+) in a solution
equals the negative log of the concentration of H+
NaOH
(sodium hydroxide)
Tums
(antacid tablets)
Pure Water
(distilled)
Soda
HCl
(hydrochloric acid)