pH + buffers

Question 1

what is the formula to measure pH

Answer 1

pH= -log [H+]

Question 2

what is the range of human blood plasma

Answer 2

pH =7.35 – 7.45

Question 3

what is acidosis and when does it occur

Answer 3

blood pH below 7.3

Question 4

what is alkalosis + when does it occur

Answer 4

blood pH greater than 7.5

Question 5

why does pH blood need to be maintained

Answer 5

affects solubility of substrates
affects 3D structures + proteins
affects activity of biological system

Question 6

what are 6 symptoms of acidosis

Answer 6

nausea
shortness of breath
headache
increase heart rate
arrhythmia 
confusion

Question 7

what is acid definition

Answer 7

compound that donate proton + gains negative charge

Question 8

what is alkali definition

Answer 8

compound that gains protons + gains positive charge

Question 9

what is the average pH of human blood

Answer 9

pH 7.4 - slight basic

Question 10

what are the 2 main sources of acid found in human body

Answer 10

metabolic

respiratory

Question 11

what is the main acid from respiratory + describe the equation

Answer 11

CO2 dissolved in water –> carbonic acid

CO2 + H2O  H2CO3  H+ + HCO3 -

Question 12

what are the main acids that are made by metabolic

Answer 12

organic acid (lactic + uric)
inorganic (sulphuric)
keto acids

Question 13

how are organic + inorganic acids made

Answer 13

metabolism of amino acids contain sulphur + phosphorus

sulphuric acid

Question 14

how is lactic acid produced

Answer 14

anaerobic glycolysis

Question 15

what can happen if there is too much kept acids

Answer 15

cause ketoacidosis in diabetes

not produce enough insulin

Question 16

what is a buffer definition

Answer 16

chemical compound that help stabilise pH of solution removing or adding protons

Question 17

how can a buffer be formed + give example of one

Answer 17

weak acid + its conjugate base

acetic acid + sodium acetate

Question 18

name 4 different buffers

Answer 18

haemoglobin
proteins
phosphate
bicarbonate

Question 19

haemoglobin - name the acid, conjugate base + site where found

Answer 19

HHb
Hb
interior of RBC

Question 20

proteins - name the acid, conjugate base + site where found

Answer 20

Hprot
Prot
intracellular fluid

Question 21

bicarbonate - name the acid, conjugate base + site where found

Answer 21

C02 –> H2CO3
HCO3-
blood plasma

Question 22

Phosphate - name the acid, conjugate base + site where found

Answer 22

H2PO4-
HPO4-
intracellular fluid

Question 23

what is definition of buffer capacity

Answer 23

amount of cid or base that can be added to a vol of buffer before its pH changes significantly

Question 24

how is the buffer capacity measured

Answer 24

Experimentally by titration

Question 25

what is definition of dissociation constant

Answer 25

specific type of eqbm constant that measures the dissociation of a object to separate/ split reversibly into smaller components

Question 26

what is the eqn of dissociation + formula for dissociation constant

Answer 26

HA H+ + A- Kd = [H+][A-] [HA]

Question 27

what is the Henderson hasselbach equation

Answer 27

``` pH= pKa + log [A-]/[HA] HA = conc weak acid A- = conc weak base ```

Question 28

what does the pKa equal in hasselbach equation

Answer 28

pH when 50% of the HA (acid) is ionised

Question 29

what is the hardest tissue in the body + its mineral content

Answer 29

enamel | 96% mineral content

Question 30

what is the problem with enamel having a high mineral content +

Answer 30

prone to demineralisation | causing dental caries

Question 31

how is caries formed by enamel

Answer 31

``` sugars coat surface of tooth + cavity bacteria process + digest sugar --> produce lactic acid + plaque reduces pH below critical point enamel dissolved causes caries ```

Question 32

what is scientific name of enamel

Answer 32

crystalline calcium phosphate | hydroxyapatite

Question 33

what is the critical pH for the tooth

Answer 33

pH 5.2-5.5

Question 34

what does the critical pH mean

Answer 34

fluid surrounding tooth become increasingly acidic point reached below critical point tooth mineral dissolves stops being saturated with Ca2+ and phosphate

Question 35

why is saliva important in the mouth

Answer 35

acts as buffer | causing normal resting pH of mouth not to fall under pH 6.3

Question 36

what are the 3 buffers in saliva

Answer 36

phosphate proteins bicarbonate

Question 37

how is protein as a buffer in saliva

Answer 37

not very effective --> charged groups form peptide bonds

Question 38

how is phosphate as a buffer in saliva

Answer 38

good buffer but not concentrated enough in saliva to be effective

Question 39

how is bicarbonate as a buffer in saliva

Answer 39

major buffer in saliva

Question 40

what is the equation of the buffer in saliva with bicarbonate

Answer 40

HCO3- + H+ H2CO3 CO2 + H2O

Question 41

what happens to the buffer equation in saliva when acid is produced by bacteria

Answer 41

equation shifts RIGHT acid neutralised by bicarbonate CO2 lost to atmosphere

Question 42

what is carbonic acid one in mouth

Answer 42

1.3 mmol/L

Question 43

how would you use hasselbach eqn to find the pH in the mouth

Answer 43

pH = pKa +(bicarbonate flow rate/ carbonic acid conc)

Question 44

what is the pK for bicarbonate

Answer 44

6.1