Unique Nature of Pure Water
What type of bond holds water molecules together?
Hydrogen bonds
What is the average salinity of seawater?
About 35 parts per thousand (ppt)
What is the pH range of most ocean water?
Between 7.8 and 8.4
What gas is primarily responsible for ocean acidification?
Carbon dioxide (CO₂)
What are the two main forms of carbon in the atmosphere?
Carbon dioxide (CO₂) and methane (CH₄)
Why is water considered a polar molecule?
Because it has a positive end (hydrogen) and a negative end (oxygen)
What two elements make up most of the dissolved salts in seawater?
Sodium and chloride
What ion is most abundant in seawater?
Chloride ion (Cl⁻)
When CO₂ dissolves in seawater, what acid is formed?
Carbonic acid (H₂CO₃)
Name one biological process that adds carbon dioxide to the atmosphere.
Respiration or decomposition
What property allows water to stick to itself?
Cohesion
How does temperature affect seawater density?
Colder water is denser than warmer water
What is meant by the “principle of constant proportions”?
The ratio of major ions in seawater remains nearly constant, even when salinity changes
What ion decreases in concentration as ocean acidification increases
Carbonate ion (CO₃²⁻)
Name one process that removes carbon from the atmosphere.
Photosynthesis or ocean absorption
Why does ice float on liquid water?
Ice is less dense because its molecules form a rigid, open structure when frozen
Why does surface water in tropical regions have lower density?
It is warmer and often has lower salinity due to rainfall
What gas is most soluble in cold seawater?
Carbon dioxide (CO₂)
How does ocean acidification affect marine organisms like corals and shellfish?
It weakens their shells and skeletons made of calcium carbonate
What is the largest carbon reservoir on Earth?
The ocean
How does water’s high specific heat affect Earth’s climate?
It allows oceans to absorb and store heat, moderating global temperature changes
What process causes vertical movement of water due to density differences?
Thermohaline circulation
How does salinity affect the freezing point of seawater?
Higher salinity lowers the freezing point
Why is ocean acidification considered a “carbon sink problem”?
The ocean absorbs excess atmospheric CO₂, which disrupts the natural carbon balance and lowers pH
How do fossil fuels impact the carbon cycle?
Burning them releases stored carbon, increasing atmospheric CO₂ levels