physical properties

Question 1

what causes the Physical states (liquid, gas, solid) to change states

Answer 1

addition or loss of heat - breaks or forms bonds (this takes a certain amount of energy)

Question 2

7 water characteristics

Answer 2

High heat capacity - important for life in oceans
High surface tension
Density controlled by salinity, temp, pressure
Heat required to change forms e.g. from liquid -> gas
Low viscosity -> Viscosity decreases with increasing temp
Sound transmitter
Transparent

Question 3

what cycle is water important for

Answer 3

hydrologic cycle + the transfer of heat between the oceans and atmosphere

Question 4

what is ionic bonding

Answer 4

atoms stick together through the donation of an electron from one atom to the other

Question 5

what is covalent bonding

Answer 5

stick together by sharing electrons rather than donating them

Question 6

what is a hydrogen bond

Answer 6

weak bond formed when a charged part of a molecule having polar covalent bonds forms an electrostatic interaction with a substance of opposite charge
- easily and rapidly formed and broken under normal
biological conditions

Question 7

why is water described as The universal solvent

Answer 7

Water can dissolve more things than any other natural substance – especially salts, which dissociate into their component ions (e.g. Na+, Cl-) in water

Question 8

what 3 things does Solar energy at a given point vary with

Answer 8

• Latitude (affects declination; Earth-location to Sun angle)
• Date (affects angle of planet; interacts with declination to define seasons)
• {Lat. + Longitude + Date} also defines cloud and dust that reflects light incident with the atmosphere

Question 9

why do North and south poles get light at lower intensity compared to equator

Answer 9

due to curvture of the earth - Earth tilt = 23 degrees relative to the sun

Question 10

what range of light do organisms use to photosynthesise

Answer 10

400-700nm

Question 11

how do you work out the light at a given depth

Answer 11

rearrange the equation to calculate K (only thing that indicates a physical property of the water - tells us how mercy the water is)
- Z is measured in positive numbers in m, and the calculated k is a positive number (unit m-1)
- Coastal water (mercier than open ocean water) will have much higher K value
- Bigger K value = mercier waters

Question 12

what can decrease the light irradiance with depth

Answer 12

its absorption by various components of seawater as it travels downward e.g. plankton

Question 13

what does light absorption depend on

Answer 13

the frequency/colour of that light

Question 14

what colours/frequencies does water absorb

Answer 14

• Water absorbs light at different frequencies to the atmosphere
• tends to absorb red spectrum (yellows and oranges too) – these colours will not show at depth as they are being absorbed by the ocean
• What appears as colour is light that is NOT absorbed e.g. Chl appears green because green is NOT absorbed

Question 15

Specific Heat definition

Answer 15

Amount of energy change when the temperature of 1g of the substance changes by 1 °C
- Heat energy is NOT equivelent to temperature - heat naturally flows down temp gradient

Question 16

Why is the sea salty

Answer 16

• Rain – lands on land where a certain amount of the ground will dissolve into the water that has fallen – eventually this will go to rivers (also adding dissolved material like ions) - and to the sea where it evaporates leaving behind the stuff that has dissolved e.g. salt

Question 17

top 5 elements dissolved in water

Answer 17

chloride
sodium
magnesium
sulphate
calcium

Question 18

what is Water density (g cm-3) a function of

Answer 18

• Temperature – heating something will cause it to expand + become less dense
• Salinity – atoms of salt will fit between the spaces of the atoms in the water molecules – gets heavier
• Depth (i.e. relates to pressure)
• Salinity has NO units – measure it by looking at how well it conducts electricity
• Cold water = more dense – molecules tend to cwtch up more

Question 19

what is Thermohaline circulation driven by

Answer 19

• in parts where its not driven by wind, circulation is driven by density gradients from temperature and salinity variation

Question 20

how does Thermohaline circulation work

Answer 20

• During sea ice formation, salt is expelled (brine rejection) - so sea ice is mostly fresh + the surrounding water gains additional salt and increases density
• Ice = 8% less dense than cold water – it will float
• Cold salty water will sink to the bottom and get pushed around in a conveyer system – drives the movement of water from different ocean basins to replace it
• Adding salt makes the formation of ice more difficult