AICE Marine Science AS Level Chapter 1 ESQs

1a: Through the use of an annotated diagram, describe covalent bonding in a water molecule

Diagram should include:
two hydrogen molecules
one oxygen molecule
single lines between the oxygen molecule and each hydrogen molecule

1b: Explain how water changes state from a liquid to a gas with reference to hydrogen bonds

energy is added through heat;
the molecules begin to move;
breaks hydrogen bonds;
molecules are able to move freely/randomly/away from each other;
create gaseous state

1c: When creating the solid form of water, ice, individual water molecules link together through the attractive forces of hydrogen bonds, forming a lattice structure. State how this change in structure affects the density of ice compared to liquid water

ice is less dense than water

1d: Explain how the change you identified in 1c impacts organisms in Arctic ecosystems

ice floats;
acts as a thermal insulator for water below;
provides habitat for organisms like algae to grow

1e: Using knowledge gained in your practical, predict the temperature of the water below the ice in the arctic ecosystems mentioned in 1d and suggest a reason why

water temperature will be below 0C due to increased salinity;
from removal of fresh water through freezing

2a: Define the term salinity

concentration of dissolved salts in seawater

2b: Outline the effect evaporation and freezing have on salinity

evaporation/freezing reduces freshwater; increases salinity

2c: Explain why the salinity of water in the open ocean tends to be higher than that near the coastlines

(fresh)water from runoff/rivers/estuaries/melting glaciers;
enters oceans/dilutes sweater (near coast);

2d: Explain how salinity and temperature affect the density of seawater creating layers within the ocean, and how mixing of these layers occurs

as salinity increases, density decreases;
as temperature increases, density decreases;
water with higher density will sink;
water with low temperature/high salinity will create bottom layer;
where different density waters come together mixing will occur;
mixing occurs along the thermocline/halocline

3a: Complete a copy of Table 1.6 by calculating the mean dissolved oxygen concentration for each environment

River mouth = 10.5
Open ocean = 6.9
Tropical lagoon = 3.3

3b: Describe how means were calculated for each environment

all collections were added for an environment;
that number was then divided by the total number of collections/3

3c: Compare the data for the three environments

Lagoon has lowest concentration;
DO concentration decreases as salinity increases

3d: Suggest explanations for the differences in D0 concentration in these habitats

Lagoon has the lowest concentration because:
higher temperature than open ocean/river;
solubility of oxygen decreases with higher temperatures;
less turbulence/wave action than in ocean/river;
waves increase gas dissolution;
more evaporation due to shallow waters;
leads to higher salinity;
solubility of oxygen decreases with higher salinity
River has the highest concentration because:
fresh water has greatest oxygen solubility;
tends to have the lowest temperature;
fast-moving rivers tend to have a lot of mixing/turbulence

4a: Identify the 'best' technique for the scientist to collect pH data from the same ten sites where temperature data was collected, and how they would ensure the results are reliable

The scientist should use a pH probe. Probe is placed at same depth for all readings/Multiple readings are taken and means are calculated

4b: Suggest reasons why the technique you chose in part (a) would be the best choice in this instance

easy to use in field situation;
digital read out produces actual number on pH scale;
less subjective to interpretation;
not qualitative;
quantifiable data collection as ions are measured through electrical impulses

4c: In a healthy ocean, state the pH levels you would expect to find

pH of 8.2; accept 8.1-8.3

4d: A student plotted the data collected by scientists on the graph seen in Figure 1.17. Identify the error made by the student when graphing his data and explain why it is incorrect

Data should be plotted on as a bar graph; because the data is discrete, not continuous. Points can be plotted +/- 1/2 the smallest square.

4e: Using the data in Table 1.7, plot a graph of the pH values on a copy of Figure 1.17

adds a named second vertical axis;
appropriate scale so data takes up more than half of available space;
points are plotted correctly

4f: To what extent does the graph support a correlation between sea surface temperatures and ocean pH?

collection sites with higher temperature have a higher pH

5a: Sketch an annotated diagram depicting the creation of an ionic bond formed from a sodium atom and a chloride atom

Diagram should include:
one chloride atom
one sodium atom
The outer layer electron in the sodium atom being transferred over to the unpaired electron in the outer layer of the chloride atom

5b: Complete a copy of Table 1.8 with each compound's bond type, chemical formula and chemical name.

Bond types:
ionic
covalent
hydrogen
Chemical name:
calcium carbonate
glucose
water
Chemical formula:
CaCO3
C6H12O6
H20

6ai: Define solute

the substance dissolved by a solvent

6aii: Define solvent

a material capable of dissolving other substances

6b: Suggest a reason why scientists think a warming ocean may have higher salinity

increased temperatures increase evaporation rates leading to higher salinity rates;
increased temperatures increase movement of water molecules making it a more effective solvent

6c: State the most abundant ionic compound in seawater

sodium chloride

7a: State the term used to describe the region of a water column where there is a drastic change in water temperature

thermocline

7b: State the approximate range of depths during which this drastic temperature change occurs

200-600m

7ci: State the depth at which the dissolved oxygen concentration is 0.4mL^-1

500-600m

7cii: State the temperature at 1000m

9C

7di: State the name for the region of the ocean with extremely low oxygen concertation at 500m deep

oxygen minimum layer

7dii: Explain why the oxygen at this level is so low

not enough light for photosynthesis;
no oxygen production;
animals are present;
animals use oxygen for respiration;
amount of oxygen consumed is larger than the amount of oxygen produced

7e: Oxygen concentrations begin to rise after 500m deep. Explain how that is possible

as temperature of the water decreases, solubility increases;
colder water has greater solubility so oxygen is less likely to leave solution;
less decomposition is happening, reducing the need for oxygen by bacteria;
pressure increases, increasing the solubility of oxygen;
organisms have reduced food sources, so need less oxygen for respiration