lecture 2 Flashcards
what is the process involved in releasing O2 in the atomosphere?
photosynthesis
describe the dehydration and hydrolysis reactions
dehydration= removing water in order to form a bond
Hydrolysis= adding water in order to break a bond
describe a water molecule
-each water molecule has a 2 slightly positive ends and 1 slightly negative end
- polar molecule
- can only bond with four other water molecules
- a high number of hydrogen bonds between water molecules allows for the cohesion of water, making it liquid.
what are the four important properties of water
1) solvent
2) cohesion, adhesion, tension
3) moderation of temperature
4) density
solvent
What is solvation and what is hydration?
solvation= solid dissolving into a solution
hydration= solvation for which the solvent is water
solvent
why can water dissolve polar and ionic substances but not those that are nonpolar?
nonpolar substances (i.e fatty acids) dont have any charges therefore no dipoles are created, thus no reactions/charges to play with
solvent
describe the process of hydration?
when anions and cations are separated from eachother and the solid dissolves ( i.e. NaCl)
- the orientation of Na is different from that of Cl
- Na attracts negative charges = oxygen
(- )charge attracts cations (+ charge)
+ charge attracts anions(- charge)
solvent
why is sugar polar?
when placed in water, it forms hydrogen bonds with the molecules on the outer surface, while water is repeatedly removing monosaccharides from the solid. Eventually a homogenous aqueous solution is formed by monosaccharides randomly distributing itself throughout the volume of water.
water is a univeral solvent
how can proteins dissolve in water?
proteins can only dissolve in water if they have ionic and or polar regions on their surface
solvent
what is the degree of polarity of a protein dependent on?
dependent on the types of amino acids that make it up.
adhesion
what is adhesion?
adhesion is the clinging of one substance to another, particulalrly if they have charged groups of atoms on their surface.
- adhesion is responsible for creating the meniscus on a graduated cylinder.
cohesion
what is cohesion?
cohesion is the process by which molecules of the same substance stay together (stick together)
ex: plants use cohesion to obtain water to the top of the plant from the roots, againt the force of gravity.
cohesion and adhesion
what process does cohesion and adhesion participate in?
they are the basis of capillary action, where water is moving in narrow tubes against gravity.
tension of water
what is surface tension?
surface tension is the measure of difficulty based on breaking or stretching a surface of a liquid ( due to cohesion )
why does water have a strong surface tension?
water has a strong surface tension because of the strong attraction between the hydrogen bonds (stronger than those between water molecules and air molecules)
moderation of temperature
what are the three physical states in natural environments and what states their differences?
- solid
- liquid
- gas
->degree of hydrogen bonding
what happens when heat energy is added to water?
the heat added breaks the hydrogen bonds reducing the degree of cohesion between the molecules
- the heat first attacks the hydrogen bonds which then causes the water molecuels to move faster
what is the difference between heat and temperature?
heat= the total amount of energy associated with the movement of atoms and molecules in a body of matter.
temperature= the average speed of molecules
what is specific heat
specific heat is the amount of heat that must be absorbed or lost for 1g of a substance to change in temperature by 1 degree.
- water has a high specifc heat = meaning that is can absorb a high amount of heat before its temperature increases, causing water to have a better ability to resist temperature changes.
- waters ability to aborb and release heat with little temperature changed allows for stability.
when is heat released to the environment by water?
heat is release when the hydrogen bonds are formed which slows down the cooling process of water. ( slow process )
Difference between perspire and transpire?
perspire= ability to cool the surface of the skin
transpire= water transpires from leaf surfaces, cooling them down
T or F
ice contains more stable hydrogen bonds than those found in water?
true
- each water molecule in ice is bounded to four of its neighbors forming a 3d crystal in which the molecules are spaciously arranged. (takes up more volume but less dense= can float on a body of water )
- hydrogen bonds in liquid water are transient, therefore they are constanly breaking and reforming. (takes up less volume but more dense)
what is ionization?
the process of water molecules breaking apart and dissciating.
- water molecules ionize into hydrogen ions (H+) and hydroxide ions (OH-)
what are acids?
acids increase the H+ concentration of a solution, donates the H+ to solutions
- purple color on pH
