Chapter 4 Biomolecules In water Flashcards
(71 cards)
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
Water is polar because
Oxygen is more electronegative then hydrogen which is why the molecule is polar
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 HThe 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
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
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
Hydrogen bonding between the hydroxyl group of an alcohol and water looks like what
R
\
O
l
H
:
O
/ \
H HWhat does H bonding between the carbonyl group of a Ketone and water look like
R1 R2
\ /
C
ll
O
:
H
l
O
\
HExample of hydrogen bonding between peptide groups in polypeptides
H R
l l
N C
\ / \ / H \ /
\/ \/ \/
C
ll
O
:
H
l
N
/\ H / \ / \
C CWhat does a strong hydrogen bond look like
R
l
O
l
H
: ↕️
O
\ //
- P
/What does a weaker hydrogen bond look like
R
l
O
l
H
.
.
.
O
//
\
- P
/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
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
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-
Water has which chemical property
It is very polar
Water tends to stick to other water molecules the primary reason for this is due to which attractive force
Hydrogen bonds
The hydrogens of water will mostly hydrogen bond to the non-bonding electron pairs of which atoms
Oxygen
Nitrogen
Fluorine
Which of the following functional groups increase the water solubility of a molecule
Alcohol
Carboxylate
Amine
Ammonium
What is a hydronium ion
Water with an extra H+
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
What is the constant for Keq
1.8x10^-16
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
At neutral pH what does the equation look like
[H+]=[OH-]= 1.0x10^-7
-log[H+]=-log[OH-]= -log(10^-7)
pH=pOH=7
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
