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Chemistry 30 - CLS > Acid and Base Review > Flashcards

Acid and Base Review Flashcards

1
Q

whats the end point

A

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

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2
Q

whats the titrant

A

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

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3
Q

steps for weak acid calculation type 2

A
  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
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4
Q

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

A

H2PO4-(aq) <–> HPO42-(aq)

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5
Q

how do you know what form an indicator is in

A

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

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6
Q

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

A

below 7

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7
Q

how do you predict the equivalence point

A

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

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8
Q

can a buffer system have a strong species in it

A

no

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9
Q

when do buffers function best

A

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

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10
Q

whats pKa

A

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

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11
Q

what are polyprotic acids and bases

A

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

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12
Q

how do you recognize a polyprotic base

A

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

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13
Q

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

A

you are dealing with a strong base

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14
Q

what happens at the equivalence point of a titration curve

A

the acid and base have completely reacted to neutralize

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15
Q

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

A

that your starting with a strong acid

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16
Q

where does the sample go during a titration

A

In the flask on the counter thats underneath the little tube

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17
Q

approximation rule for acids and bases

A

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

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18
Q

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

A

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

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19
Q

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

A

the lungs

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20
Q

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

A

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

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21
Q

where do you put the titrant during a titration

A

its held in the little tube at the top

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22
Q

whats a buffer

A

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

23
Q

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

A
  • 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
24
Q

how do you recognize a polyprotic acid

A

any acid that contains more then 1 H

25
Q

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

A

> 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

26
Q

steps for weak acid calculation type 1

A
  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
27
Q

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

A

on or very close to 7.0 pH

28
Q

what does it mean when a substance is amphoteric/amphiprotic

A

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

29
Q

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

A

your dealing with a weak acid

30
Q

whats a titratiom curve

A

a graph of changes in pH during a titration

31
Q

can a buffer just be one chemical

A

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

32
Q

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

A

you are dealing with a weak base

33
Q

whats the Ka expression

A

Ka = [products]/[reactants]

34
Q

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

A

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

35
Q

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

A

the conjugate acid base pair dihydrogen phosphate and hydrogen phosphate ions

36
Q

whats the equivalence point

A

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

37
Q

what does a buffer do/whats its purpose

A

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

38
Q

how do you calculate the pKa of a substance

A

pKa=−log(Ka)

39
Q

what does the shape of a titration curve depend on

A

the strengths of the acids and bases used

40
Q

why can a buffer resist pH change

A

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

41
Q

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

A

H2Co3(aq) <–> HCO3-(aq)

42
Q

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

A

whichever exponent is lower is the bigger number

43
Q

whats the sample

A

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

44
Q

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

A

at least one strong species

45
Q

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

A

above 7

46
Q

5 steps for predicting brownsted lowry reactions

A
  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
47
Q

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

A

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

48
Q

whats the pH of water

A

7

49
Q

what are indiators

A

weak acids that have a different colour than their conjugate base

50
Q

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

A

based on its pH range or transition range

51
Q

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

A

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

52
Q

whats the Kb expression

A

Kb = Kw/Ka of conjugate acid

53
Q

steps for weak base calculation

A
  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

Chemistry 30 - CLS (15 decks)

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