Chapter 4 Biomolecules In water Flashcards Preview

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Flashcards in Chapter 4 Biomolecules In water Deck (71):
0

Water is polar because

Oxygen is more electronegative then hydrogen which is why the molecule is polar

1

Water is a bent molecule because

Since the two bonds to hydrogen plus the two pairs of non-bonding electrons form a near tetrahedral (4 available bonds)
..
H-O: (:are paired and non bonding)
l
H

If we look at the oxygen and hydrogen only it's going to be a bent molecule

2

One unique feature of water is that

The hydrogen ion of one water can hydrogen bond to the unpaired electrons of another oxygen to form bonds between waters
.. ..
H-O: ⬅️ H-O:
l l
H H

3

The positive hydrogen can interact with a non-bonding pair of electrons on atoms such as

Oxygen, nitrogen, and fluorine

H+acceptor
\ / \\ // \ / \ / \ / \\ /
C N O C O N
ll : : ll : :
O H H O H H
: l l : l l
H O O H N N
l l l l l l
O N
l l
H+donor
Ketone, amine, ether, aldehyde,alcohol, other amines

4

In hydrogen bonding the alcohol -OH will

The alcohol will bond hydrogen to most other oxygen that will have non-bonding electrons they also want to bond to nitrogen that has extra electrons

5

Hydrogen bonding in ice

Both liquid and solid water forms large numbers of hydrogen bonds with each other

It forms a crystalline structure and this is the case of ice

6

Hydrogen bonding between the hydroxyl group of an alcohol and water looks like what

R
\
O
l
H
:
O
/ \
H H

7

What does H bonding between the carbonyl group of a Ketone and water look like

R1 R2
\ /
C
ll
O
:
H
l
O
\
H

8

Example of hydrogen bonding between peptide groups in polypeptides

H R
l l
N C
\ / \ / H \ /
\/ \/ \/
C
ll
O
:
H
l
N
/\ H / \ / \
C C

9

What does a strong hydrogen bond look like

R
l
O
l
H
: ↕️
O
\ //
- P
/

10

What does a weaker hydrogen bond look like

R
l
O
l
H
.
.
.
O
//
\
- P
/

11

Water solubility versus fat solubility has mostly to do with what

Water solubility versus fat solubility has mostly to do with the amount of polar and nonpolar groups on the molecule

If you see aliphatic hydrocarbons (carbons form open chains) those are not water-soluble and the more there are in the molecule the less water-soluble that module is.

Polar groups make it more soluble like alcohol (-OH), ammonium a (NH3),

carboxylates (R--C--OH)
ll
.. O
Amines (R--N--H)
l
R

12

How does water dissolved electrolytes

Water dissolves electrolytes by forming a hydration shell around both positive and negative ions

H H H
\ \ / H
O O /
/ Na+ O
H \
O H
/ \
H H

The water dissolve the salt because the N+ ions will bind them selves up with the O- side of water and hide the H+ side of water will find themselves up with the Cl- and form salvation sell around each of ions

13

Hydronium ions give up a

Hydronium ions give up a proton (H3O+) so the H+ bounces around until H2O accepts a proton and becomes a hydronium ion

Protons can bounce around in a solution

O- unpaired electrons hydrogen bond to the H+ of the other water

2H20 ↔️ H3O+ + OH-

14

Water has which chemical property

It is very polar

15

Water tends to stick to other water molecules the primary reason for this is due to which attractive force

Hydrogen bonds

16

The hydrogens of water will mostly hydrogen bond to the non-bonding electron pairs of which atoms

Oxygen
Nitrogen
Fluorine

17

Which of the following functional groups increase the water solubility of a molecule

Alcohol
Carboxylate
Amine
Ammonium

18

What is a hydronium ion

Water with an extra H+

19

What is the formula for the equilibrium of water

H2O ↔️H+ + OH-

Keq(Constant) = [H+] [OH-] ➗[H2O]
⬇️
[H2O]x Keq = [H+] [OH-]
⬇️
Kw= [H+] [OH-] (stands for)
⬇️
Kw= Keqx [H2O]

Water concentration is extremely high compared to H+ or OH- or any other solute so we move it over to the other side of the equation

20

What is the constant for Keq

1.8x10^-16

21

Kw= Keq x [H2O]
⬇️

Kw= (1.8x10^-16)x [55.5M]
(It is the sum) Kw=1.0x10^-14
(Sum of) [H+] [OH-]= 1.0x10^-14

22

At neutral pH what does the equation look like

[H+]=[OH-]= 1.0x10^-7

-log[H+]=-log[OH-]= -log(10^-7)

pH=pOH=7

23

What is the formula for all other pHs besides water

[H+][OH-]= 1.0x10^-14

-log[H+]+ -log[OH-]= -log(10^-14)

pH+pOH=14

24

How can you calculate the pH if you already know what the pOH is

14-pOH=pH

And if you know what the pH then I know how to find the pOH

14-pH= pOH

25

What is the pH of a neutral solution

7

26

What is the pH of a solution that has a pOH of 6

8

27

What is the formula for weak acids and bases

pH=pKa + log1(if equal to each other)

pH(how acidic solution is)= pKa(how acidic an H atom in a molecule is)

If equal to each other log1=0

28

The pH of a solution when an acid is half to dissociated is the

pKa

29

What is pH?

pH=-log[H+]

pOH=-log[OH-]

pH+pOH=14

30

What is the pH if something is basic

Greater than 7

31

What is the pH if something is acidic

Less than 7

32

A solution has a pH of 4.1 is this considered acidic or basic

Acidic

33

What is the Henderson -hasselback equation

pH= pKa+ log [A]/[HA]

H+ is hydrogen ion concentration
A conjugate base of acid
HA undissociated acid
p= substitute -log

34

How do you make a .1M pH 5 acetate buffer?

1. Calculate the MW of acetic acid and for sodium acetate (C2H4O2) + (C2H3O2Na)= [HA] 60 + [A]82

2.pKa= 4.76 pH=5
pH=pKa+log [A]/[HA]

5=(4.76) +log [A]/[HA]
5-4.76=log [A]/[HA]
.24=log [A]/[HA]


3. 10^(.24)=1.74
1.74= [A]/[HA]

4. 1.74 [HA]= [A]
[HA]+ 1.74[HA] =0.1M
[HA]= 0.1M/2.74
2.74 [HA]= 0.1 M
[HA]= 0.1/2.74
[HA]=0.036M (acetic acid)
[0.036]+[A]=0.1
[A]=0.1M -0.036M=0.064M(sodium acetate)


Grams:
[A]=0.064mol/L x 82g/mol = 5.24g/L
[HA]=0.036mol/L x 60g/mol=2.16g/l

35

Most buffers work best when

Within 1 pH unit of it pKa

36

Why is sodium phosphate monobasic considered an acid relative to sodium phosphate dibasic?

The monobasic has one more titratable H ion

37

What is the pH of a neutral solution

7

38

A solution has a pOH of 5 what is the pH

9

39

If a solution has a pH of 9.8 is this considered to be an acidic or basic solution

Basic

40

The pH of a solution when an acid is half dissociated is

pKa

41

Most buffers work best

Within 1 pH unit of its pKa

42

Sodium phosphate dibasic is a------ compared to sodium phosphate monobasic

Base relative to the other compound

43

Sodium phosphate monobasic is -----compared to sodium phosphate dibasic

Acid relative to the other compound

44

Definition of diffusion

Movement of molecules along a concentration gradient

High to low

45

Define osmosis

Diffusion of small molecules like (water sodium potassium chlorine phosphate sugar urea) across a semi permeable membrane

46

Define osmotic pressure

Pressure that must be applied to a solution to prevent the inward flow of water across a semi permeable membrane


How much pressure solute is putting on the membrane

47

Define oncotic pressure

Osmotic pressure exerted by the plasma proteins

48

Define osmolarity

Number of molecules of osmotically active molecules per liter of solvent

49

Define osmolality

Number of moles of osmotically active molecules per kilogram of solvent

50

Body fluid osmolality is maintained at

285-300 mOsm H2O

51

Osmolarity is independent of the type of

Solute in a solution

52

Both electrolytes and electrolytes contribute to

Osmolarity

53

Osmolarity is independent of the type of

Ions in a solution

54

Both cations and and anions contribute to

Osmolarity

55

Osmolarity of a nonelectrolyte is

1xM where M is the molar concentration of the nonelectrolyte

56

Osmolarity of an electrolyte is

nxM where n= number of ions in the electrolyte and M= molar concentration of the electrolyte

57

Osmolarity of a 1M glucose

1 OsM

58

Osmolarity of 1 M sodium chloride

2 OsM

59

Osmolarity of 1M calcium chloride

3 OsM

60

Osmolarity of 1M sodium phosphate tribasic

4 OsM

61

What would happen if you placed a membrane in water with a high concentration of salt in the tube membrane?

The amount of pressure it would take to push that water back across the membrane would be equal to the osmotic pressure exerted by solutes in the tube

62

What is the osmolarity if the number of solutes on the inside are equal to the outside

Isotonic

63

What is the osmolarity it the number of solute is higher inside the cell then outside the cell

Hypotonic

64

What is osmolarity if the number of solute is higher outside the cell than inside the cell

Hypertonic

This could cause the cell to crenate

65

What is the gas law equation

PV=nRT

66

What is the equation if we rearrange the gas law for osmolarity

II=RT (ic(ions in conc.)+ ic+ ic....)

Isotonic is .32OsM
C= concentration of each substance
I= The number of ions or solutes

-ex: sucrose= i=1, NaCl= i=2, CaCl2=3

67

Isotonic Celine is .9% sodium chloride if you are asked to make the solution how would you do it?

Since percent means per 100 you add 0.9 g of sodium chloride to each 100 mL of water this would be the same as 9 g of NaCl into 1 L of water

9g=1000mL of water

68

What is the osmolarity of isotonic sodium chloride

Since my osmolarity is equal to iC where i= number of ions or molecules per formula mass and c= the molarity of the formula, calculation would be as follows

MW of NaCl= 58.5g/mol
(9g/L)/ (58.5g/mol)=.152mol/L
NaCl has i=2

.153mol/L x2= .306 OsM

69

To make an isotonic solution of NaCl what that is .32 OsM what molarity of NaCl would you need to make?

.32/2= .16

70

To make a isotonic magnesium chloride solution .30 OsM what molarity of magnesium chloride would you need to make?

.30/3= .1M