ch 5

Question 1

what is the size of dissolved material

Answer 1

less than 1 nm

Question 2

why is colloid study important in chem oceanography

Answer 2

things we think are dissolved may be particulate- have different processes dictating their cycling

hydrophobic substances in or on colloids

Question 3

where are colloids found

Answer 3

in dispersion medium- larger than 1 nm- diff from dissolves

Question 4

what differentiates dissolevd matter from colloid

Answer 4

colloid doesnt pass semipereable membrane

elevates boiling point
lowers freezing point
no effect on osmotic pressure

Question 5

what is the similarity between dissolved and colloidal matter

Answer 5

doesnt settle

Question 6

homogenous, clear, doesnt settle

Answer 6

solution

Question 7

doesnt settle, not clear

Answer 7

colloiids

Question 8

settles, heterogenous, cloudy

Answer 8

suspension

Question 9

example of solution

Answer 9

saltwater

Question 10

example of colloid

Answer 10

virus in seawater or milk

Question 11

example of suspension

Answer 11

mud

Question 12

larger versus smaller bubbles and stokes law

Answer 12

smaller bubbles can collapse, higher SA to volume ratio- rise slower - negative answer to stokes law- lose a lot of air as they rise because they rise slowly

Question 13

surface tension in small versus large bubbles

Answer 13

higher in smaller bubbles

Question 14

cyanobacteria and gasses- stokes law

Answer 14

they produce N2- helps them rise and be clsoer to light for photosynthesis- they have acess to N2 to fix it

Question 15

what is marine snow

Answer 15

decomposing organic matter

their density is very slighly higher than water byut sometimes can get stuck in the therocline since in the thermocline the density increases to equal the marine snow

Question 16

how is organic carbon shipped into the deep ocean

Answer 16

larvacean mucus houses and fecal pellets

Question 17

what is stokes equation exact for

Answer 17

spherical and smooth paritcles and small slowly sinking particles that are not much denser than water

less than 100 um

Question 18

why does stokes law not apply to fast sinking particles

Answer 18

because fast sinking large particles with lwoer SA to volume ratio vause TURBULENCE due to friction and drag of water- changes u in denominator of stokes equation

stokes overestimates speed for fast praticles due to drag

Question 19

small sphere falling under action of gravity in viscous medium reaches a constant sinking velocity

Answer 19

stokes law

Question 20

how do we operationally define suspended versus settingg mattter

Answer 20

caught in sediment trap or caught in water sampler

Question 21

what are the filters we use to operationally define dissolved or particulate matter

Answer 21

first membrane filter 0.45 um then glass fibre filer

Question 22

what are the issues with using filters

Answer 22

there are 3 nominal pore sizes

different manufacturers define the sizes differently - different methods to calcuate nominal pore size

they state the absolute retention siez- some can be squeezed through

Question 23

biology, why do we need distinction bw dissolved and particulate matter

Answer 23

distinguish bw living and recently living

vs

material exuded or excreted or broken down

Question 24

chem, why do we need distinction bw dissolved and particulate matter

Answer 24

distinguish bw suspended solids/ micelles aggregates

vs

single molecules, ions, dimers, oligomers