CHAPTER 8: ACIDS & BASES
STANDARD SL-L & HL-M
STUDY GUIDE
SECTION 8:1
1.
What are the major differences between Arrhenius, Bronstead-Lowery and Lewis definition of
acid and bases
Arrhenius defines acids as a species that increases the concentration of hydrogen ions in solution
and a bases is a species that increases the concentration of hydroxide ions in solution.
Bronstead-Lowry defines acids as a species that is a proton (H+) donor and a base as a proton
(H+) acceptor.
Lewis defines acids as an electron pair acceptor and a base as an electron pair donor
2.
What does amphoteric (amphiprotic) mean? Something that can act as an acid or base
3.
What enables certain species to be amphoteric? They must have the ability to accept a H+ or
donate a H+.
4.
Give an example of how water can act as an acid.
NH3 + H2O  NH4+ + OH-
5.
Give an example of how water can act as a base.
H2CO3 + H2O  HCO3 - + H3O+
6.
Explain what a dative bond is and how it relates to Lewis acids and bases?
A dative bond is a bond that forms when both electrons in the pair comes from the same
molecule. A Lewis bases contribute the electrons with Lewis acids thus creating a datative
bond.
7.
What is a ligand and how does it relate to Lewis acids and bases?
A ligand is a Lewis base that donates a lone pair and usually surrounds Lewis acids in a fixed
ratio.
8.
What is a complex ion and how does it relate to Lewis acids and bases? A complex ion forms
when a ligand surrounds a metal ion (usually a transition metal).
9.
What role do transition metals play in Lewis acids and bases? Transition metals can be Lewis
acids when surrounds by ligands that are Lewis bases
10.
Do Book Exercises #1-6 Pgs 148-150 (see answers in back of book)
Exercise #1 Remember that a conjugate acid of a base will be what a base becomes when it
gains a H+ (accepts a proton) That is why SO3 2- (base) becomes HSO3 – (conjugate acid)
Exercise #2 Remember that a conjugate base of an acid is what an acid becomes when it
loses a H+ (donates a proton) That is why H3PO4 (acid) becomes H2PO4 – (conjugate base)
Exercise #3 Remember acids donate a H+ and bases accept H+.
Exercise #4 Remember that Lewis bases have unshared pairs of electron and therefore act
as electron donors and Lewis acids are often transition metal ions or molecules without unshared
pair of electrons
Exercise #5 Remember that a ligand is a Lewis base.
Exercise #6 Remember that Lewis bases can also be B-L bases but Lewis acids are not. Transition
metals are not B-L acids.
SECTION 8.2
11.
12.
What is another name for soluble bases? Alkalis
13.
Write the balanced equation for water with the following bases:
A. NH3 + H2O  NH4 + + OHB. Na2CO3 + H2O  HCO3 - + Na+ + OHC. Na2O + H2O  2NaOH
D. NaHCO3  H2CO3 + Na+ + OH-
14.
What common ion is produced by all the reactions above?
OH-
15.
What is litmus and what is it used for? Used to determine if a substance is acidic, basic, or
neutral.
16.
Write an equation for the reaction of zinc with hydrochloric acid
Zn + 2HCl  ZnCl2 + H2
17.
What group(class of compounds) form when an acid reacts with a metal or a base.
Salts
18.
What gas always forms when an acid reacts with a base H2
19.
What is the other product besides a salt that is produces when an acid reacts with a base?
H2 O
20.
What term is used when an acid reacts with a base
neutralization
21.
Define:
a.
b.
c.
22.
Titration the procedure that determines the molarity of an unknown
acid to a know molarity of a base or an unknown molarity of a base to a
known molarity of an acid
equivalence point the point where an acid is completely neutralized by a
base or a base is completely neutralized by an acid
standardization finding the molarity of an acid or base
How can soil that is too acidic to grow certain plants be improved so that the plants will grow?
Treat the soil with lime (CaO) which is a base when added to water
23.
What is used to help relieve acid indigestion?
Antacids are weak bases of magnesium hydroxide and aluminum hydroxide
24.
If acid indigestion is caused by an increase in the production of hydrochloric acid in the
stomach, show the balanced equations for the reaction of this acid with an antacid with
aluminum hydroxide as the active ingredient
6HCl + 2Al(OH)3 2 AlCl3 + 6 H2O
25.
Write the balanced equation of the reaction between rain water(containing carbonic acid) and
limestone.(see the information box on page 173)
H2CO3 + CaCO3 --> Ca(HCO3)2
Why is baking soda traditionally used for most bee stings but vinegar is used to treat wasp
stings.
Bee strings are slightly acidic but wasp stings are slightly basic
26.
27.
Besides carbonic acid, there has been an increase in other acidic gases such as sulfur dioxide
and nitrogen dioxide. What is the contributing factors for the increase in each gas?
Sulfur in the air comes from burning high sulfur coal which reacts with oxygen to produce SO2 which
reacts with the water in the air to produce H2SO3 and nitrogen dioxide comes from combustion of
gasoline which produces produces HNO3 + HNO2
***Go back to Chapter 3 pg 62-63 to answer questions #28-32
28.
Metal oxides reacts with water to produce alkaline (basic solutions). Write the balanced
equation between CaO and water.
CaO + H2O  Ca(OH)2
29.
Nonmetal oxides react with water to produce acidic solutions. Write the balanced equation
between P4O10 with water
P4O10 + H2O  H3PO4
30.
Write the balanced equation between sulfur trioxide and water
SO3 + H2O  H2SO4
31.
Show how aluminum oxide is amphoteric by writing the balanced equations between
aluminum oxide and sulfuric acid and aluminum oxide and a sodium hydroxide
Al2O3 +3H2SO4  Al2SO4 + 3 H2O (acting as a base)
Al2O3 + H2O + NaOH  Al(OH) – (acting as an acid)
32.
Describe the acid-base character of the oxides of period 3 elements Na to Ar. For sodium oxide
and sulfur trioxide, write the balanced equations to illustrate their acid-base character.
Na2O + H2O 2 NaOH
SO3 + H2O  H2SO4
33.
Do exercise #7 page 154 & #8 page 156 see answers in the back of the book
#7 ***Be sure to know these equations
#8 Remember that both strong acids and strong bases with the same concentration will
conduct electricity equally. Weak acids or weak bases will be the weakest conductor b/c they
do not completely dissociate in water.
SECTION 8.3
34.
How does the amount that an acid or base dissociate determine if it is strong or weak?
Strong acids and strong bases completely dissociate into H+ ions and OH- ions respectively
Weak acids and weak bases only partially dissociate into H+ ions and OH- ions respectively
35.
Name three strong acids(Give name and formula)
Hydrochloric acid (HCl), Nitric acid (HNO3), Sulfuric acid (H2SO4)
36.
Name three weak acids (Give name and formula)
Ethanoic acid also known as acetic acid (CH3COOH or HC2H3O2), Carbonic acid (H2CO3),
and Phosphoric acid (H3PO4)
37.
Name four strong bases (Give name and formula)
Lithium hydroxide (LiOH), Sodium hydroxide (NaOH), and potassium hydroxide (KOH), and
Barium hydroxide (Ba(OH)2),
38.
Name two weak bases (Give name and formula) Ammonia (NH3) and Ethylamine (C2H5NH2)
39.
Amines are organic bases. What makes up the structure of an amine. Hydrocarbons(CxHy)
combined with amino groups (NH2)
40.
An amino acid is an organic acid. What makes up the structure of an amino acid
An amino group (NH2) and a carboxyl group (COOH)
41.
The “A” in DNA stands for acid. What acid is this referring to? Phosphoric acid (H3PO4)
42.
Outline three different methods to distinguish between equimolar solutions of a propanoic acid
and nitric acid. State how the results would differ for each acid.
Since propanoic acid is a weak acid and nitric acid is a strong acid; (1) the pH of nitric acid
would be less than that of propanoic acid, (2) nitric acid would have a greater conductivity
than propanoic acid b/c there are more H+ ions in the solution to conduct the current, (3)
nitric acid would have a faster reaction rate than propanoic acid b/c of the concentration of H+
is greater in nitric acid.
43.
Three methods that can be used to distinguish between equimolar solutions of a strong base
and a strong acid are: 1.) adding magnesium to each (2.) adding sodium hydroxide to each and
(3.) adding hydrochloric acid to each. Explain how each method and the results of each would
be used to distinguish between the strong acid and strong base.
(1.)Adding magnesium to a strong acid will result in H2 gas bubbles but strong bases will
not react with a magnesium(2) adding sodium hydroxide which is a strong base will neutralize
the strong acid and since neutralization is an exothermic reaction, the temperature will increase.
(3) adding hydrochloric acid which is a strong acid will neutralize the strong base and since
neutralization is an exothermic reaction, the temperature will increase.
44.
Calcium carbonate is added to separate solutions of hydrochloric acid and ethanoic acid of the
same concentration. State one similarity and one difference in the observation you could make.
Both acids would produce CO2 gas which would be observed by bubbling and calcium
carbonate would appear to be dissolving. However the rate of the reaction and the formation
of the bubbles (CO2 gas) would be more rapid in HCl than in C2H5COOH b/c HCl is a strong
acid and C2H5COOH is a weak acid
Exercise #9 pg 157 Remember that for every 10 x the acid is diluted, the concentration of H+ decreases
by 10x and the pH increases by 1.
Exercise #10 page 158 Remember that NaCl is made up of a cation from a strong base and an anion from
a strong acid so it is neutral. Also remember that all organic acids (CxHyCOOH)and organic bases
(CxHyNH2) are weak.
Be sure to study Practice Problems Pg159-160 #2,3,5,6,7,8,9,10,11,12.
#2 Remember that memorize the strong and weak acids and bases and that strong acids have the lowest
pH and strong bases have the highest pH values. Also remember that strong acids and strong bases have
the highest electrical conductivity and that if they both have equal concentrations that they will conduct
electricity equally
#3 Remember that acids react with metals to produce hydrogen gas as one of its products
#5
0.100 mol/dm3HCl has a pH of –log [H+] or –log .1 = 1
0.010mol/dm3HCl has a pH of –log [H+] or –log .01 = 2
0.100 mol/dm3 NaOH has a pOH of –log [OH-] or –log .1 =1 and a pH of 14-1 = 13
0.010 mol/dm3 NaOH has a pOH of –log [OH-] or –log .01 = 2 and a pH of 14-2 = 12
#6 Remember that metal oxides act as bases b/c metal oxides form bases when added to water and
nonmetal oxides act as acids b/c nonmetal oxides form acids when added to water
#7 This has an error in it. The [H+] will decrease if the pH increases. Remember that the [H+] decrease
by 10x every time the pH increases by one and the [H+] increases when the pH decreases by the same
factor.
#8 &10 The [H+] will decrease if the pH increases. Remember that the [H+] decrease by 10x every time
the pH increases by one and the [H+] increases when the pH decreases by the same factor.
#9 Be sure to memorize the strong and weak acids and bases
#10 The [H+] will decrease if the pH increases. Remember that the [H+] decrease by 10x every time the
pH increases by one and the [H+] increases when the pH decreases by the same factor.
#11 (a) –log .1= 1 HCl is a strong acid and completely dissociates
(b) >1 less than 7 b/c ethanoic acid is a weak acid and only partially dissociates
#12 (a) Strong acids are acids that completely dissociate in water whereas weak acids are acids that only
partially dissociate in water. HCl  H+ + Cl- and C2H5COOH = C2H5COO- + H+
(b) (i) See WS question #44
(ii) 2HCl + CaCO3  CaCl2 + H2CO3 (H2CO3 immediately breaks up into CO2 + H2O) so the
equations should be 2HCl + CaCO3  CaCl2 + CO2 + H2O
(iii) 1.25 g /100.09 =.0125 moles CaCO3 HCl to CaCo3 is 2:1 so 2 x .0125 = .0250 moles
Molarity is 1.50 moles/dm3 so Volume in dm3 would be .025/1.5 = .0167 dm3 or 16.7 cm3
(iv) PV = nRT
V = nRT/P (.0125)(8.31)(273)/(1.01x105) = 2.8 x 10-4 dm3