Acids and bases

Question 1

What are the three definitions for acid and bases?

Answer 1

1. Arrhenius
2. Bronsted-Lowry
3. Lewis

Question 2

What is the Arrhenius definition of acid-base?

Answer 2

Acid- will dissociate to form an excess H+ in solution
Base- Will dissociate to form an excess of OH- in solution
This is limited to aqueous acids and bases. they usually contain H in the beginning or OH at the end.

Question 3

What a bronsted Lowry acid and base?

Answer 3

Acid- A species that donates H+ ions
Base- species that accepts H+ ions
It is not limited to aqueous solutions.
Usually occurs in pairs, called conjugate acid-base pairs

Question 4

What is the Lewis acid-base definition?

Answer 4

Acid- an electron pair acceptor.
Base- electron pair donor
Different Names:
coordinate covalent bond formation, complex ion formation, nucleophile-electrophile interactions.

Question 5

What are amphoteric species?

Answer 5

One that reacts like an acid in a basic environment and like a base in acidic environments.

Question 6

What is an amphiprotic species?

Answer 6

In a Bronsted-Lowry, it can gain or lose a proton .

Question 7

What are some amphoteric species?

Answer 7

Water, HSO4- also note Al, Zn, Pb, Cr, Zwitterions .

Question 8

If an acid is formed from anions with names that end in -ide, the nomenclature is ?

Answer 8

Prefix hydro, ending ic

Question 9

Oxyacids that end in -ite or ic have a nomenclature of?

Answer 9

end in -ous acid or ic acid respectively.

Question 10

what is Autoionization?

Answer 10

When an amphoteric compound reacts with itself, like water.

Question 11

What is Kw?

Answer 11

It is the water dissociation constant Kw= 10^-14. OH and H ions each 10^-7 if perfectly pure water

Question 12

What is the equation for pH and pOH

Answer 12

pH= -log[H+]= log 1/[h+]

pOH=-log [OH-]= log 1/[OH-]

Question 13

Concept understanding. -log( n x 10^-m) =

Answer 13

-log(n)-log(10^-m) = m - log(n), p value around m-0.n

Question 14

What are strong acid and bases?

Answer 14

they completely dissociate in their component ions in aqueous solutions. They go to completion.

Question 15

If the concentration of an acid or base is not far greater than 10^-7, what must one consider?

Answer 15

Autoionization of water. It is not negligible at this point (note ex on pg 339).

Question 16

What are some strong acids?

Answer 16

HCl, Hbr, HI, H2SO4, HNO3, HClO4

Question 17

What are some strong bases?

Answer 17

NaOH, KOH, soluble hydroxides of group IA.

Question 18

What does it mean when a pH of a solution is greater than 14 or less than 0?

Answer 18

this implies there is a very high concentration of strong acids or bases.

Question 19

What is the definition of weak acids and strong bases?

Answer 19

They partially dissociate in aq solutions.

Question 20

What is the acid dissociation constant?

Answer 20

Ka = [H2O+][A-]/[HA] . the smaller Ka, the weaker the acid. Less than 1 is a weak acid

Question 21

What is the base dissociation constant?

Answer 21

Kb = [B+][OH-]/[BOH] . the smaller b, the weaker the base and the less it will dissociate. less than one is a weak base.

Question 22

How can the dissociation constant be determined if one species or conjugate is known.

Answer 22

Ka acid x Kb conjugate = Kw (10^-14) . vice versa too

Question 23

When is approximation of x valid?

Answer 23

when x is less than 5% of the initial concentration or Ka is 100 times smaller.

Question 24

What is neutralization reaction?

Answer 24

Acids and bases may react with each other to forma salt and often water(but not always). in general it is a process that goes to completion.

Question 25

What is hydrolysis?

Answer 25

When salt ions react with water to give back the acid or base.

Question 26

What occurs between a strong acid and strong base?

Answer 26

Products form equal molar amounts of the salt and base. They also neutralize each other and result in a pH of 7. They do not react with water because they are inert conjugates.

Question 27

What happens when a weak base and strong acid react?

Answer 27

A salt is formed but often no water will be formed because weak bases are not hydroxides. The weak base can be reformed through hydrolysis.

Question 28

What happens when a weak base and acid react ?

Answer 28

Depends on the relative strength of each, can go either way of the spectrum.

Question 29

What is the the equation to calculate unknown titrand?

Answer 29

NaVa =NbVb . normality and volume.

Question 30

What is the Henderson Hasselbalch equation

Answer 30

used to estimate pH or pOH of a buffer solution pH=pKa + log [A]/[HA] . When conjugate base = weak acid, pH= pKa cause log 1 is 0. This occurs at half equivalence and is optimal. It quantifies the relationship between pH and pKa and vice versa.

Question 31

How do you calculate the pH of a buffer when acid or base is added?

Answer 31

Calculate the the concentration in the final solution, NV=NV, then use the henderson equation.

Question 32

What is equivalent?

Answer 32

It is defined as one mole of the species of interest .

Question 33

What is normality?

Answer 33

The concentration of acid or base in equivalents solution.

Question 34

What is polyvalent?

Answer 34

acid and base are those that can donate or accept multiple electrons. The normality of a solution containing polyvalent species is the molarity of the acid or base times the number of protons it can donate or accept.

Question 35

What are titrations?

Answer 35

they are used to determine the concentration of a known reactant in a solution.

Question 36

What is a titrant?

Answer 36

the concentration that is added slowly to the titrand

Question 37

What is the titrand?

Answer 37

an unknown concentration but a known volume

Question 38

What is the half-equivalence point?

Answer 38

it is the midpoint of the buffering region, in which half of the titrant has been protonated, or deprotonated. Thus HA=A- and buffer is formed

Question 39

What is the equivalence point?

Answer 39

indicated by the sleepes slope in a atitration curve, it is reached when the number of acid equivalents in the original solution equals the number of base equivalents acid, or vice versa.

Question 40

What are indicators?

Answer 40

they are weak acids or bases that display different colors in their protonated or deprotonated states. The indicator chosen should have a pKa close to the pH of the expected equivalence point. the endpoint of a titration is when the indicator reaches its final color.

Question 41

If multiple buffering regions are observed, then ...

Answer 41

it is polyvalent.

Question 42

What are buffer solutions?

Answer 42

Consist of a mixture of a weak acid and its conjugate salt or vice versa, they resist large fluctuations in pH.

Question 43

What are buffering capacities?

Answer 43

refers the ability of a buffer to resist changes in pH. Maximal buffering capacity is seen within 1 pH point of the pKa of the acid in the buffer solution.