Titration Of Amino Acids

Question 1

Which of these donates the proton? Acid or base

Answer 1

Acid

Question 2

Strong acid examples:

Answer 2

HCL & H2SO4

Question 3

Weak acid examples

Answer 3

H2CO3 & CH3COOH

Question 4

Equation of HCL disassociation

Answer 4

HCL —> H+ Cl-

Question 5

H2CO3 disassociation equation:

Answer 5

H2CO3 <——-> H+ + HCO3-

Question 6

Ka =

Answer 6

[H+][A-]
———
[HA]

Question 7

How to convert H+ concentration to Ph

Answer 7

Ph = -log [H+]

Question 8

What is blood’s [H+]?

Answer 8

40nEq/L / (0.00000004Eq/L)

Question 9

Instrument for measuring pH?

Answer 9

pH meter (for liquids)

Question 10

Henderson-Hasselbalch Eq:

Answer 10

⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀[A-]
pH = pKa + log ——
[HA]

Question 11

What is a buffer system?

Answer 11

Weak acid/base with its conjugate (acid/base)

Question 12

Maximum buffer capacity is when x=x ?

Answer 12

Acid=Base & pH=pKa (log(1) =0)

Question 13

Buffer range:

Answer 13

pH = pKa+1 ~ pKa-1

Question 14

How many amino acids are in nature?

Answer 14

300

Question 15

What is the central carbon in an amino acid connected to?

Answer 15

An R-group, Amino group, Carboxyl group and H atom

Question 16

What amino acids is an exception to the structure? And what’s the difference?

Answer 16

Glycine ; has an H atom for its R-group
^ this causes it to be neutral

Question 17

Are amino acids that form proteins L Or D Isomers

Answer 17

L isomers

Question 18

pKa of Carboxyl group?

Answer 18

2-3

Question 19

pKa of Amino group?

Answer 19

9-10

Question 20

When pH>pKa of ionizable R-group is it protonated or deprotonated ?

Answer 20

Deprotonated

Question 21

order of deprotonation of Amino acid groups

Answer 21

COOH > NH3- > R group
(They turn to COO+ , NH2)

Question 22

Isoelectric point is:

Answer 22

The pH at which net charge of a molecule is 0

Question 23

Equations of PI
(2 ionizable, acidic aa, basic aa)

Answer 23

2 ionizable groups: pKa1+pKa2/2
Acidic amino acids ^^^^^^^^^^^
Basic amino acids: pka2+pka3/2

Question 24

What does titration measure?

Answer 24

Concentration

Question 25

Is glycine acidic or basic?

Answer 25

Neutral lol

Question 26

pKa1 of glycine?

Answer 26

2.3

Question 27

pKa2 of Glycine?

Answer 27

9.6

Question 28

pi of glycine?

Answer 28

~6

Question 29

pKa1 of Aspartic acid?

Answer 29

2.1

Question 30

pKa2 of Aspartic acid?

Answer 30

3.9

Question 31

pKa3 of Aspartic acid?

Answer 31

9.7

Question 32

pKa1 of Arginine?

Answer 32

2.2

Question 33

pKa2 of Arginine?

Answer 33

9

Question 34

pKa3 of Arginine?

Answer 34

12.5

Question 35

Functions of Graduated cylinder, beaker, Erlenmeyer flask and burette

Answer 35

Graduated: liquid total volume Beaker: contain the liquid Erlenmeyer flask: Shaking Burette: deliver specific amount

Question 36

What solutions do we need for alanine lab?

Answer 36

Weak acid (alanine) Strong base (NaOH) Distilled water

Question 37

Steps of alanine NaOH lab

Answer 37

1) Fill burette with NaOH 2) Add 10ml of alanine to a flask 3) Add a few drops of HCL to it 4) Measure initial pH 4.2) Immerse probe in solution 5) Add 1ml of NaOH 6) Shake well & measure 7) Repeat until 2nd buffer region

Question 38

What was the initial pH of Alanine?

Answer 38

1.61