Warm-Up 12/18/2016
The equation below represents a balanced
chemical reaction:
2 Mg(s) + O2(g)  2 MgO (s)
How many moles of MgO are produced when
7.2 moles of O2 react with excess Mg?
a)3.6 moles
b)14.4 moles
c)22.3 moles
d)29 moles
Complete the following chart
pH
[H +]
[OH -]
pOH
3
.001
1 x 10 -11
11
10
1 x 10 -10
1 x 10 -4
4
2.5
3 x 10 -3
3.2 x 10 -12
11.5
3.7
2 x 10 -4
5 x 10 -11
10.3
Practice
Complete the following chart
pH
[H+]
[OH-]
pOH
4.5
5.6
3 x 10-5
4.6 x 10-9
Practice Problems
•Determine if each of the following solutions
is acidic, basic, or neutral:
+
-10
•a. [H ] = 6 x 10
•b. [OH-] = 3 x 10-2
•c. [H+] = 2 x 10-7
-7
•d. [OH ] = 1 x 10
•What is the pH and the pOH of the following?
•1) 0.001 M HCl
•2) 0.0034 M NaOH
•3).0025 M H2SO4
•4) .00725 M Ca(OH)2
Molarity
A measurement of the concentration of a
solution
Molarity (M)= is equal to the moles of
solute (mol) per liter of solution
M = mol/ L
Practice
Calculate the molarity of a solution
prepared by mixing 1.5 g of NaCl in 500.0
mL of water.
Practice
How many grams of LiOH is needed to
prepare 250.0 mL of a 1.25 M solution?
Practice
What is the concentration of 250.0 mL of
0.60 mol of HCl?
What volume of 0.7690 M LiOH will contain
55.3 g of LiOH?
Practice
What is the concentration of 35.0 mL of
0.0556 moles of KCl?
How many grams of KCl is needed to prepare
50.0 mL of a 0.10 M solution?
Molarity and Dilutions
•The act of diluting a solution is to simply
add more water (the solvent) thus leaving
the amount of solute unchanged.
•A relationship can be established such that
•M1V1=M2V2
Molarity and Dilution
Given a 6.00 M HCl solution, how would
you prepare 250.0 mL of 0.150 M HCl?
Practice
Calculate the molarity of a solution
prepared by diluting 25.0 mL of 0.05 M
potassium iodide with 50.0 mL of water?
Practice
•A 50.0 gram sample of NaOH is dissolved in
0.600 L of water. What volume of this
solution would be needed to create a 1.5 L
solution that is 0.200 M NaOH?
Practice
• A concentrated solution of sulfuric acid, H2SO4,
has a concentration of 18.0 M. How many
milliliters of the concentrated acid would be
required to make 250. mL of a 1.00 M H2SO4
solution?
Practice
•53.4 mL of a 1.50 M solution of NaCl is on
hand, but you need some 0.800 M solution.
How many mL of 0.800 M can you make?
Warm-Up 12/20/2016
•What volume is needed to store 105
grams of helium gas at 202.6kPa and
122.5˚C?
Neutralization Reactions
Neutralization reactions occur when an
acid and base react
The products of any neutralization reaction
is always a SALT and WATER
Indicators change color in during a
neutralization reaction
Salts
•A salt is a compound that contains a
metal and nonmetal other than H and
OH
•Examples: NaCl, MgF2, FeSO4
Examples of Neutralization Reactions
•Neutralization reactions are double
displacement reactions
•HCl + KOH  H2O + KCl
•Examples:
•a. H2SO4 + Mg(OH)2  H2O + MgSO4
•b. H3PO4 + LiOH  H2O + Li3PO4
Titration
Titration is a neutralization reaction that is
used to determine the concentration of an
unknown substance
In a titration, a substance with a known
concentration is used with an indicator
Burette-the common lab equipment used to
deliver a liquid substance to another liquid
substance
Titration Curve
Indicators
Indicators are organic substances
that change color in the presence
of acids and bases
Examples: Red Cabbage is pink in
acids and blue-green in bases
Phenolphthalein
Indicator Ranges
Indicator Kind
Litmus
Methyl Orange
Phenolphthalein
pH range
5–8
3.1 - 4.4
8.3 - 10.0
Example Question
• The chart below shows the characteristics of several
common acid-base indicators
Indicator
pH Range
Color Range
Bromocresol Green
3.8-5.4
Yellow to Blue
Congo Red
3.0-5.0
Blue to Red
• Which indicator would appear to be yellow in a solution
PhenolaRed
6.8-8.2
with
hydrogen ion concentration
of 1.0 x 10-7 ? Yellow to Red
Indigo Carmine
11.6-13.0
Blue to Yellow
Solving for Titrations
•How many mL of a 3 M NaOH solutions are
required to completely neutralize 20.0 mL of
1.5 M HCl?
Practice # 2
•What is the molarity of a solution of LiOH
if 15.0 mL of the solution is required to
neutralize 20.0 mL of 2M HCl?
Practice # 3
What volume, in mL, of 0.25 M Acetic Acid
is required to neutralize 30.0 mL of 0.05 M
of Cesium Hydroxide?
Practice # 4
•What volume of 0.115 M HClO4 solutions is
needed to neutralize 50.00 mL of 0.0875 M
NaOH?
Practice # 5
•What volume, in mL, of 0.128 M HCl is
needed to neutralize 2.87 g of NaOH?
Homework
• If it takes 54 mL of 0.1 M NaOH to neutralize
125 mL of an HCl solution, what is the
concentration of the HCl?
•If it takes 25 mL of 0.05 M HCl to neutralize
345 mL of NaOH solution, what is the
concentration of the NaOH solution?
A Broader Definition of Acids and Bases
In the more inclusive Brønsted-Lowry model,
an acid is a hydrogen-ion donor and a base is a
hydrogen-ion acceptor.
When a Brønsted-Lowry acid donates a
hydrogen ion, a conjugate base is formed.
When a Brønsted-Lowry base accepts a
hydrogen ion, a conjugate acid is formed.
Two substances related to each other by the
donating and accepting of a single hydrogen
ion are a conjugate acid-base pair.
Identifying Conjugate Acid-Base Pairs
• Identify the conjugate acid-base pairs in this reacton.
•A hydrogen ion is donated by HClO2, which is the
Brønsted-Lowry acid in the forward reaction.
•The resulting conjugate base is ClO2–.
•The base in the forward reaction is H2O, which
accepts a hydrogen ion to form the conjugate acid
H3O+.