Acid and Base Review

Question 1

whats the end point

Answer 1

the point where the sample chemical has all been reacted and the titrant is now reacting with the indication causing a colour change

Question 2

whats the titrant

Answer 2

the reagent/solution in the burette that is added to the contents of the flask

Question 3

steps for weak acid calculation type 2

Answer 3

1. write the BL reaction equation for the substance n the question with water
2. make an ICE table
3. use the pH given to get the H3O concentration and then fill in the missing values in the table
4. use the equilibrium concentrations to solve for Ka

Question 4

whats the equation for the major intracellular buffer system in the cell plasma***

Answer 4

H2PO4-(aq) <–> HPO42-(aq)

Question 5

how do you know what form an indicator is in

Answer 5

if the indicator contains H, its in an acid form; if the indicator is just its symbol with no H its in its base form

Question 6

where will the equivalence point be if a weak base is titrated

Answer 6

below 7

Question 7

how do you predict the equivalence point

Answer 7

pick out the steepest part of the curve and then determine the point that is in the middle of that section

Question 8

can a buffer system have a strong species in it

Answer 8

no

Question 9

when do buffers function best

Answer 9

when the pKa of the conjugate weak acid used is close to the desired working range of the buffer; the more equal amounts of conjugate pairs and the higher their concentration, the longer the buffer will last

Question 10

whats pKa

Answer 10

measure of the acidity of a compound, specifically how easily a molecule donates a proton

Question 11

what are polyprotic acids and bases

Answer 11

species that can accept or donate more than 1 hydrogen ion/proton

Question 12

how do you recognize a polyprotic base

Answer 12

by the size of the negative charge (anything greater then 1- is polyprotic)

Question 13

what does it mean if the titration curve starts with a pH between12-14

Answer 13

you are dealing with a strong base

Question 14

what happens at the equivalence point of a titration curve

Answer 14

the acid and base have completely reacted to neutralize

Question 15

what does it mean when the line on a titration curve starts at a pH between 0 and 2

Answer 15

that your starting with a strong acid

Question 16

where does the sample go during a titration

Answer 16

In the flask on the counter thats underneath the little tube

Question 17

approximation rule for acids and bases

Answer 17

if [initial acid]/Ka is >1000 then approximation rule applies

Question 18

how do you determine whether it should be an acid or base calculation when dealing with an amphoteric/amphiprotic substance

Answer 18

compare the Ka and Kb for the substance and whichever is bigger determines the type of weak species calculation

Question 19

where does the H2CO3(aq) in the blood buffering system come from

Answer 19

the lungs

Question 20

what is the normal pH of blood plasma and how is this maintained

Answer 20

7.4; maintained by the intracellular buffer system in the cell plasma

Question 21

where do you put the titrant during a titration

Answer 21

its held in the little tube at the top

Question 22

whats a buffer

Answer 22

a solution that can resist pH change upon the addition of an acidic or basic components

Question 23

what are the 6 rules regarding listing entites in a BL reaction

Answer 23

• ionic compounds dissociate into ions
• strong acids dissociate into ions
• strong bases dissociate into ions
• weak acids are left as is
• weak bases are left as is
• always add water

Question 24

how do you recognize a polyprotic acid

Answer 24

any acid that contains more then 1 H

Question 25

how do you know what percentage to put above the arrow in your final BL reaction when no strongs are present

Answer 25

>50% when the strongest acid is higher on the table than the strongest base <50% when the strongest acid is lower on the table than the strongest base

Question 26

steps for weak acid calculation type 1

Answer 26

1. write the BL reaction equation for the substance in the question with water 2. mace an ICE table from the equation 3. check to see if approximation rule applies 4. use Ka expression to solve for the equilibrium concentrations

Question 27

where will the equivalence point be when a strong acid and base are titrated

Answer 27

on or very close to 7.0 pH

Question 28

what does it mean when a substance is amphoteric/amphiprotic

Answer 28

it can either donate or accept an H ion meaning that the substance can act as both an acid and a base

Question 29

what does it mean when the line on a titration curve starts at a pH between 2-6.5

Answer 29

your dealing with a weak acid

Question 30

whats a titratiom curve

Answer 30

a graph of changes in pH during a titration

Question 31

can a buffer just be one chemical

Answer 31

no, it must consist of a weak conjugate acid-base pair

Question 32

what does it mean if the titration curve starts with a pH between 12 and 7.5

Answer 32

you are dealing with a weak base

Question 33

whats the Ka expression

Answer 33

Ka = [products]/[reactants]

Question 34

what is a common biological buffer system*****

Answer 34

the carbonic acid and hydrogen carbonate ion conjugate acid base pair is the major buffering system in the blood and other body fluids

Question 35

what is the major intracellular buffer in cell plasma***

Answer 35

the conjugate acid base pair dihydrogen phosphate and hydrogen phosphate ions

Question 36

whats the equivalence point

Answer 36

the point where there has been enough moles of titrant added to be equal to the moles of sample content so that the reaction is complete and the sample has been neutralized

Question 37

what does a buffer do/whats its purpose

Answer 37

it is able to neutralize small amounts of added acid or base, making the pH of the solution remain relatively stable

Question 38

how do you calculate the pKa of a substance

Answer 38

pKa=−log(Ka)

Question 39

what does the shape of a titration curve depend on

Answer 39

the strengths of the acids and bases used

Question 40

why can a buffer resist pH change

Answer 40

because the two components (conjugate acid and conjugate base) are both present in appreciable amounts at equilibrium

Question 41

what is the equation for the major buffering system in blood and other body fluids ***

Answer 41

H2Co3(aq) <--> HCO3-(aq)

Question 42

how do you tell which number is bigger when dealing with numbers multiplied by 10 to the power of something

Answer 42

whichever exponent is lower is the bigger number

Question 43

whats the sample

Answer 43

the reagent/solution that is put in the Erlenmeyer flask; the solution that is getting added to

Question 44

what do all titrations require to be able to show a defined equivalence point

Answer 44

at least one strong species

Question 45

where will the equivalence point be if a weak acid is titrated

Answer 45

above 7

Question 46

5 steps for predicting brownsted lowry reactions

Answer 46

1. list all entites 2. labek all entities as WA, WB, SA, SB, or SI 3. identify strongest acid and strongest base 4. use those 2 to write a BL reaction 5. chose arrow and add percenage

Question 47

how do you determine the strongest indicators among other acids and bases

Answer 47

based on the Ka value of the indicator which you can use to help you fit the indicator into the table

Question 48

whats the pH of water

Answer 48

7

Question 49

what are indiators

Answer 49

weak acids that have a different colour than their conjugate base

Question 50

how is the appropriate acid/base indicator for a titration chosen

Answer 50

based on its pH range or transition range

Question 51

rules for picking your arrow at the end of making a BL reaction

Answer 51

if there are strongs present then use a one way completion arrow%; if there are no strongs present then use an equilibrium arrow

Question 52

whats the Kb expression

Answer 52

Kb = Kw/Ka of conjugate acid

Question 53

steps for weak base calculation

Answer 53

1. write the BL equation 2. make an ICE table from the equation 3. convert Ka to Kb 4. check for the approximation rule 5. use a Kb expression to solve for the equilibrium concentrations 6. convert to pH or any other needed values