Solubility Solubility: maximum amount of solute that can be
dissolved in a given quantity of solvent at a specific temperature.
Even for very soluble substances, theres a limit to how much can be
dissolved in a given amount of solvent.
Slide 4
Saturation Saturated solution: solution at the limit Solution
has as much solute as it can dissolve at that T (temperature) If
more solute is added it wont dissolve and will only precipitate out
In a state of dynamic equilibrium: rate of dissolving = rate of
crystallizing
Slide 5
Saturation Unsaturated solution: solution under the limit
Solution hasnt reached the limit of how much solute it can dissolve
at that T If more solute is added it will dissolve Supersaturated
solution: solution above the limit Solution contains higher than
saturation concentration of solute Any slight disturbance/seeding
causes crystallization/precipitation of excess solute
Ex: At 20 C, solubility of NaCl (s) in water is 36g/100mL.
Slide 8
Saturation Concentration ([ ]): quantitative measure (a number)
of how much solute is contained in an amount of solvent. Ex:
Slide 9
Saturation Concentrated solution: qualitative term; large
amount of solute dissolved. Dilute solution: qualitative term;
small amount of solute dissolved.
Slide 10
Q: At 20 C, KCl (s) solubility is 34g/100g of water. In the
laboratory, a student mixes 45g KCl (s) with 100g of water at 20 C.
A.How much KCl (s) will dissolve? ___________ B.Is the solution
saturated? ___________ C.What is the mass in grams of solid KCl
that wont dissolve? __________________________
Slide 11
Q: At 50 C, the solubility of NaNO 3(s) is 114g/100g of water.
How many grams of NaNO 3(s) are needed to make a saturated solution
of 50g of water at 50 C?
Slide 12
Practice! Practice: p. 223 # 4-10, p. 226 #1-7, 9, 10 Read: p.
220-226
Slide 13
Flame Tests
Slide 14
Concentration NOT THE TYPE YOU NEED FOR A TEST
Slide 15
Concentration Concentration: quantitative measure of solute in
solvent. How much solute is dissolved in solvent. Can be
represented by different units, there are different ways of stating
concentration. Most commonly used: molar concentration or molarity
= _________ = C C =
Slide 16
Ex 1: What is the molar concentration of 4.00L solution with
1.54mol NaOH in it?
Slide 17
Ex 2: What is the molarity of 0.23mol of sodium sulphate
dissolved in 500mL of water?
Slide 18
Ex 3: 4.00g of NaOH is dissolved in 250mL of solution. Whats
the molarity of NaOH (aq) ?
Slide 19
Ex 4: How many mL of 0.400M NaOH solution will contain 1.00g of
NaOH?
Slide 20
Ex 5: How many moles are in 2.00L of 4.00mol/L solution of
NaCl?
Slide 21
Ex 6: What is the mass of NaCl in the previous example?
Slide 22
Ex 7: Whats the volume when 0.500 moles of NaOH make a
3.00mol/L solution?
Slide 23
Ex 8: Calculate the mass of Na2CO3 required to make 3.5L of a
1.2mol/L solution.
Slide 24
Ex 9: What volume of 0.500M solution can be made from 12.00g of
NaCl?
Slide 25
Ex 10: Whats the concentration of a solution with 53.2g of
CaCl2 in 5000mL of water?
Slide 26
Other Concentration Calculations (% mass, % volume, ppm)
Percent by mass: Percent by volume:
Slide 27
Ex: Whats the % by mass of NaCl if 9.0g of NaCl is added to
91.0g of water?
Slide 28
Ex: Whats the % by volume of ethanol if 15.0mL of ethanol is
added to 85.0g of water?
Slide 29
Parts per Million (ppm) Parts per million (ppm): same units top
and bottom multiplied by a million (10 6 ) Useful for very low
concentrations
Slide 30
Ex: What is the ppm (m/v) of NaCl if 5.9mg of NaCl is dissolved
in 500mL of water?
Slide 31
Concentration of Ions in Solution 1. Write a balanced
dissociation equation or ionization equation: Ex: Al 2 (SO 4 )
3(aq) 2. Use the mole ratio and the Factor-Label Method to find the
concentration of the ions: Ex: 1.00M Al 2 (SO 4 ) 3(aq). Find [Al
3+ ] and [SO 4 2- ].
Slide 32
Slide 33
Ex: A barium hydroxide solution is 2.00mol/L. Find [Ba 2+ ] and
[OH - ].
Slide 34
Practice! Practice: p. 316 #1-4, 6, p. 214 #2-12, 15 Read: p.
314-215, p. 203-213
Slide 35
Strengths/Weaknesses of Acids/Bases
Slide 36
Bronsted-Lowry A/B Ionization/Dissociatio n Equations FILL IN
THE HANDOUT AS WE GO
Slide 37
How to write equations for ACIDS: General Equation: HA donates
H + (proton) to H 2 O (acts as a base):
Slide 38
How to write equations for ACIDS: Therefore, a conjugate
acid-base pair consists of two substances related to each other by
donating/accepting a proton (H+). Ex:
Slide 39
How to write equations for ACIDS: The hydronium ion (H 3 O + )
forms from attraction between H + and polar H 2 O. Both H 3 O + and
H + are used to measure the strength of an acid (they are used
interchangeably).
Slide 40
Practice: Identify the conjugate acid- base pairs in the
following equations: 1. 2.
Slide 41
Practice: Identify the conjugate acid- base pairs in the
following equations: 3. 4.
Slide 42
Practice: Identify the conjugate acid- base pairs in the
following equations: 5. 6.
Slide 43
Polyprotic Acids! The last 3 equations are examples of
polyprotic acids! Polyprotic acids can lose more than one proton (H
+ ): Ex: So they can react with H 2 O more than once to produce
many H 3 O + ! # times an acid can react = # Hs at the front; each
time it reacts, it gets weaker
Slide 44
Favouring Stronger Products In all of the above equations, the
products are stronger acids and bases than the reactants. Remember:
strong acids completely ionize. Weaker acids dont and we can
represent this with a forward and reverse arrow. Ex:
Slide 45
How to write equations for BASES: 1. If it has an OH -
(hydroxide): simply write the dissociation equation General
Equation: (these are strong bases!) Ex: NaOH (aq)
Slide 46
How to write equations for BASES: 2. If it has no OH-
(hydroxide): split the cmpd into its ions and use the anion (-ve
one). React the anion with H 2 O to produce OH - Determine the
other product (its the anion gaining a H + ). Remember: acids lose
H +, bases gain H + General Equation: (these are weak bases!)
Slide 47
Ex: Na 2 CO 3
Slide 48
Ex: Na 3 PO 4
Slide 49
Ex: NH 3
Slide 50
Polyprotic Bases Polyprotic bases: can accept more than one
proton (H + ) so it can react with H 2 O many times to produce many
OH - (hydroxide ions): Ex: # times it can react = # charge
Slide 51
Strong vs. Weak Acids/Bases: The stronger the acid, the more H
3 O + it produces, the higher its [H3O+], and the more forward the
ionization moves (>99% ionization): General Equation: (There are
7 strong acids and theyre listed on the data sheet)
Slide 52
Strong vs. Weak Acids/Bases: The stronger the base, the more OH
- it produces, the higher its [OH - ], and the more forward the
dissociation moves (>99% dissociation): General Equation:
(Strong bases: have OH- and a Group 1 metal/Alkali metal)
Slide 53
Strong vs. Weak Acids/Bases: Weak acids and bases only
partially ionize and dissociate (
