Unique Nature of Pure Water
What type of bond holds two hydrogen atoms and one oxygen atom together in a water molecule?
Covalent bond
What is the average salinity of ocean water?
35 parts per thousand (ppt)
What is the pH range of normal seawater?
About 7.8-8.3 (slightly basic)
What gas dissolves into seawater and causes ocean acidification?
Carbon dioxide
What is the main gas responsible for the oceans role in the carbon cycle?
Carbon Dioxide
What type of bond forms between water molecules that gives water its cohesion?
Hydrogen bond
Which two ions make up most of seawaters salinity?
Sodium and Chloride
What process removes salts from seawater naturally?
Evaporation leaves salts behind, but precipitation and sedimentation remove ions over time.
What acid is formed when carbon dioxide reacts with seawater?
Carbonic acid
Name one way carbon enters the ocean.
Diffusion from the atmosphere or decomposition of organism
Why is water called a polar molecule?
Because it has a partial positive charge on hydrogen and partial negative on oxygen.
What happens to the density of seawater as salinity increases?
Density increases
What is meant by the principle of constant proportions?
The ratios of major ions in seawater remain constant, even if salinity changes.
How does ocean acidification affect marine organisms with shells?
It dissolves calcium carbonate, weakening shells and skeletons.
What form of carbon do marine plants use during photosynthesis?
Dissolved carbon dioxide
What property allows water to stick to other surfaces like glass or plant tissue?
Adhesion
What physical property of water decreases as temperature increases?
Density
Why does seawater resist sudden changes in pH?
Because of its buffering capacity from carbonate and bicarbonate ions.
Since the Industrial Revolution, by how much has ocean pH decreased approximately?
By about 0.1 units
What happens to carbon when marine organisms die and sink to the seafloor?
It becomes stored in sediments as carbon compounds.
How does waters high heat capacity help regulate Earths climate?
It absorbs and releases heat slowly, stabilizing temperature changes.
Why does the ocean have layers (surface mixed layer, thermocline, deep zone)?
Due to density differences caused by temperature and salinity variations.
How does the solubility of gases like oxygen and carbon dioxide change with temperature?
Colder water holds more dissolved gas.
Why does acidification make it harder for coral reefs to grow?
It reduces carbonate ion availability, which corals need for calcium carbonate skeletons.
Explain how the biological pump moves carbon in the ocean.
Photosynthesis fixes CO2 into biomass, organisms die/sink, carbon is transported to deep ocean.