Chapter 2 - Water Flashcards
What are the fluid phases of water?
Gas (steam/vapor)
Liquids (Water)
What are the condensed phases of water?
Liquids (water)
Solids (ice)
Name 5 reasons why water is essential for biochemistry.
- Medium for most biochemistry reactions (transportation - taking meds)
- Common reactant
- Part of cellular components (protein, cell membrane)
- Covers 70% of earth’s surface
- Helps maintain body temperature (sweat, we dont freeze in cold)
In which phase are molecules easy to observe??
gas phase - they’re far away
Gasses are measured under what conditions??
Standard temperature and pressure (1atm, 0 degrees celsius)
Water has a high ______
specific heat, boiling point
What is the essential feature of the gas phase?
There is effectively no interaction with other molecules
Properties of gasses are essentially the same, as long as they are under_____
STP
A water molecule is ______overall
neutral
A perfect tetrahedral conformation is _______degrees, but water is ______degrees due to ______
A perfect tetrahedral conformation is 109.5 DEGREES, but water is 104 DEGREES due to the lone pairs on oxygen
How many valence electrons does oxygen have?
6
In a covalent bond, sharing is usually ______
unequal
The only time when electrons are shared completely equally in a covalent bond is when…?
covalent bond between identical atoms (N2 or O2)
Unequal sharing of electrons leads to _______
partial charges
The electronegativity scale runs from ____to____
0 to 4
On the periodic table, which elements are the most electronegative??
The elements at the top right of the periodic table
Is CO2 polar or nonpolar? why?
nonpolar because the vectors cancel each other out
What are the 2 INCOMPRESSIBLE states of water? What does this mean?
solid and liquid. the external pressure causes the molecules to not be able to move closer together
Are hydrogen bonds covalent bonds?
NO
On their own, hydrogen bonds are _____
weak
Together, hydrogen bonds form a very strong lattice structure. What does this explain about water?
Its peculiar properties
As water freezes to ice, its density…..
DECREASES
As ice melts to water, density…?
increases
At what temperature does water reach its maximum density?
4 degrees celsius
The uniqueness of water stems from which 2 things?
electronegativity difference (large)
and the geometry of its hydrogen bond interactions
The process of surrounding ions with water molecules is called…?
hydration
What is specific heat?
The amount of energy needed to increase the temperature of 1 gram of a substance by 1 degree celsius
Water acts as a _________
temperature buffer. heat loss or gain is smaller in water compared to other substances
As temperature of water increases, the H bonds _____ but dont _____
bend but dont break
Which phase of water does NOT have a high specific heat?
ICE. The H bonds cannot bend in this phase
What is the definition of an acid?
Species that increase the hydrogen ion concentration when added to water
What are bases?
Species that DECREASE the hydrogen ion concentration when added to water
NaCl dissolves in water to form a ______ solution
neutral
NH3 is a _____?
weak base
ph=
-log[H+]
What is the pH of the blood?
7.4
pka=
-logka
The flat region on a titration curve is known as the ____________ and is the numeric value of _______
buffering region, pka
All weak acids and bases are _______
buffers
What is the most significant physiological buffer?
blood bicarbonate buffer
CO2 is technically a(n)____
acid
What is 3 mol in avagadro’s number??
18 * 10^23
A chemical is more stable when it contains ______energy
less
Low pka = ____aciditiy
HIGH
low ka = ___Acidity
LOW
At what temperature does water have the smallest VOLUME
4/5 degrees celsius
Water can be considered a ____ of oxygen
hydride
Why does decane have a slight affinity for water?
induced dipole attraction
Does a substance NEED to provide OH- to be considered basic?
NO
What is the pH of our stomach acid when we’re hungry?
1-2
If pH is 5 what is the [H+] ion concentration?
0.00001 mol/L
