Acids And Bases

Question 1

Binary acids

Answer 1

-Have each atom attached to a nonmetal

Ex: HCL

Question 2

Oxy acids

Answer 2

-have hydrogen and oxygen and another element typically a nonmetal

HxEOy

(H: hydrogen
O: oxygen
E: central nonmetal element

Ex: H2SO4 H3PO3

Question 3

Carboxylic acids

Answer 3

-have COOH chain attached to a carbon chain

Ex: HCOOH, CH3COOH

Question 4

Arrhenius, definition of acids and bases

Answer 4

Acids: acids ionize [Process of forming ions from neutral molecules, typically involving a chemical reaction] in water to produce H+ ions and anions

Ex: HCl ionizes in water and produces H+(aq) + CL-(aq)

Bases: basis disassociate [break apart into individual ions] in water to produce OH ions and cations

Ex: NaOH (it is an ionic compound)
In water, it disassociates completely and produces Na+ + OH-

Question 5

Arrhenius acid base reactions

Answer 5

The H+ from the acid combines with the OH- from the base to make a molecule of H2O

The remaining cation from the base combines with the remaining anion from the acid to make a salt

Acid + base = salt + water
Ex: HCL + NAOH= NaCl + H2O

Question 6

Bronsted Lowry definition

Answer 6

Acids: The acid is a H+ donor

Base: The base is a H+ acceptor

In a Bronsted acid base reaction , an H+ is transferred

-The acid is a H+ donor and the base is a H+ accepter

Question 7

Amphoteric substances

Answer 7

-substances, I can either act as an acid or a base

Ex: HCO3- H2PO4-

Question 8

Conjugate Acids and base

Answer 8

-an acid becomes a conjugate base after donating a proton (H+)

-A base becomes a conjugate acid after accepting a proton (H+)

Ex: HCL (acid) = donates a proton Cl- (conjugate base)
NH3 (base) = accepts a proton NH4+ (conjugate acid)

-conjugate bases, have one less proton, and one less positive charge than its acid

-Conjugate acids have one more proton and one more positive charge than its base

Question 9

Strong acid strength

Answer 9

-a strong acid completely ionizes in water
-single arrows used
-acid disassociation equilibrium lies far to the right

Ex: HA produces H+ + A-
HA+ H2O produces H3O+ + A-
Ex: HCL HBR HI HNO3

Question 10

Weak acid strength

Answer 10

-weak acids partially ionized in water
-acid disassociation equilibrium lies to the left
-Double arrows are used

Ex:
HF-+ H20 (double arrows) F-+H3O+
Ex: HF H2SO3 H2CO3

Question 11

Strength of strong bases

Answer 11

-a strong base completely disassociates in water to form OH-
BOH(aq) produces B+ + OH-

Ex: NAOH LiOH KOH CA(OH)2

Weak bases: produce a small amount of OH- by accepting a proton from water to form OH- to reach equilibrium

Ex:
NH3 + H2O producers NH4+ + OH-
B+ H2O = HB+ + OH-

EX: NH3 CO3 CH3NH2

Question 12

Acid ionization constant (Ka)

Answer 12

Ka = [A-] [H3O+]/[HA]
(reactants over products)

The larger, the KA, the stronger the acid

-strong acid disassociation goes to completion so no KA

Question 13

Binary acid strength (H-X)

Answer 13

-the more electronegative X is the stronger the acid

-bond energy: the weaker the bond (lower bond energy) the stronger the acid

-Across the period: acidity increases from left to right

-Down a group acidity increases due to lower bond energy, even if electronegativity decreases slightly

strong acid: a strong acid occurs when the bond is easy to break due to low bond energy and X is very electronegative

(Weakest strongest): HF HCL HBR because Br has the lowest bond energy

Question 14

Strength of oxy acids H-O-Y

Answer 14

-the more electronegative Y is the stronger the oxy acid

-Across a period (left-right) acidity increases because electronegativity increases, which makes the H-O bond weaker

-the more oxygen atoms attached to Y the stronger the oxy acid

Question 15

Base ionization constant (Kb)

Answer 15

-larger KB = stronger base
Ex: B+ + H2O produces HB+ + OH-

Kb= [HB+] [OH-]/ [B]

Question 16

How do you find KB?

Answer 16

Ka and Kb are related for conjugate acid based pairs by the equation KaxKb = Kw

To find Kb: Kw/Ka
Kw is a constant 1.0x10^-4) at a constant temperature
-with the change of temperature, Kw changes, but [H+] always = [OH-]

Question 17

KW

Answer 17

• neutral solutions have equal concentrations of H3O+ and OH- ions

-acidic solutions have a larger concentration of H3O+ than concentration of [OH-]

-basic solutions have a larger concentration of OH- than concentration of H3O+

Question 18

Ka and Kb

Answer 18

-the stronger and acid the weaker, the conjugate base

-the stronger a base the weaker the conjugate acid

Question 19

Acidity and basicity of a solution

Answer 19

-Expressed by pH
ph = -log[H3O+]

[H3O+] = 10^-ph

Question 20

Ph vs pOH

Answer 20

pOH= -log[OH^-]

[OH-] = 10^-pOH

pH + pOH = 14.00

Question 21

Calculate pH of an acid solution

Answer 21

-in most cases, we are not given [H+] or [OH-], instead the concentrations of the acid or base is given

To calculate the pH of the solution first think of sources of [H+]
-there are two sources of H3O+ in an aq solution of an acid, the acid and the water.

-for strong acids like HCl, they disassociate completely so if the concentration of HCL = 0.10M then the concentration of H3O+ will also be 0.10M. ph = -log(0.10)

-weak acids do not disassociate completely so to calculate pH of a weak acid, set up an ice table, and assume the initial concentration of HA = 0

2. Write Ka and substitute equilibrium concentrations
3. Solve for X (concentration of H3O+)
4. Once you solved X calculate pH.

Question 22

When to use small K approximation

Answer 22

-When X is less than 5% after doing the 5% check

5% check = x/[HA] initial

If more than 5% then use the quadratic equation to solve for pH

a= 1
b= Ka
c = Ka x initial value

Question 23

Percent ionization of a weak acid

Answer 23

-A week acid partially ionizes when dissolved in water

% ionization = [A-]/[HAi] x100
-because [A-]eq = [H3O+]eq (1:1 mole ratio)
% ionization = [H3O+]/[HAi]. x100

The higher the percent ionization, the stronger the acid

Question 24

Calculations of basic solutions

Answer 24

-use Kb and pOH in calculations

Kb = kw/ka
-small x approximation if less than 5%

1. If given ph find H3O and then use kw/ka to find [Oh] which is x

Question 25

Acid-base properties of salt

Answer 25

-salts or water soluble ionic compounds Ex: KF NaCl -when salts dissolve in water, they disassociate form ions in solution KF(s) disassociates K+ + F- -the salt solution can be acidic neutral or basic

Question 26

Ph neutral, anions

Answer 26

In general, the anion (A-) is the conjugate base of an acid HA EX: Cl- is the conjugate base of HCL -And an ion that is the conjugate base of a strong acid is pH neutral Ex: Cl- is the conjugate base of a strong acid HCL, thus Cl- is pH neutral NO3- is the conjugate base of a strong acid HNO3, thus NO3- is pH neutral

Question 27

Anion as base

Answer 27

-an anion that is the conjugate base of a weak acid is a weak base Ex: F- is the conjugate base of a weak acid (HF) thus F- is a weak base and hydrolyzes in water F- + H2O = HF + OH

Question 28

Cations as acids

Answer 28

-Group one and group 2 metal cations are all pH neutral Ex: Na+ and K+ are the counter ions were strong base NaOH, thus Na+ and K+ our pH neutral Small, highly charged metals are weak acids (Al3+) (Fe3+)

Question 29

Classifying salts as acid or base

Answer 29

-a salt contains both a cation and an anion, to determine its pH: 1. Salt in which neither the cation nor the anion act as an acid or a base for pH neutral solutions Ex: NaCl KBr 2. Salt in which the cation is pH neutral, and the anion acts as a base forms basic solution. Ex: NaF KNO2 3. Salt in which the cation acts as an acid and the anion is pH neutral forms, acidic solution Ex: AlCl3 FeCl3 NH4Br 4. Salt in which the cation acts as an acid and the anion act as a base can form acidic or basic solutions. -Compare Ka and Kb Ka>Kb = acidic Ka < Kb = basic

Question 30

Determine the pH of a salt

Answer 30

1. Determine the acid and base property of the cation and anion 2. Write the corresponding chemical equations. 3. Set up ice table and write the expression of Ka or Kb to solve for x and pH

Question 31

Polyprotic acid

Answer 31

-Polyprotic acids have two ionizable protons Ex: H2SO3 H2SO4 Ka1>Ka2>Ka3

Question 32

Calculation of Polyprotic acid

Answer 32

Given [H2A], how do we calculate [HA-] [H+] pH and [A2-] 1. [HA-] [H+] and ph can be calculated from Ka1 [A2-] is calculated from the 2nd ionization equilibrium, where the final [HA-] [H+] from the first ionization is now the initial concentrations in the ice table