Unique Nature of Pure Water
What type of bond holds water molecules together?
Hydrogen bonds
What is salinity a measure of?
The amount of salt in water
What are the two most abundant ions in seawater?
Sodium and chloride
What gas is mainly responsible for ocean acidification?
Carbon dioxide (CO₂)
What process do plants and algae use to absorb carbon dioxide?
Photosynthesis
Why is water considered a polar molecule?
It has a positive and negative side
How does temperature affect the density of seawater?
Cold water is denser than warm water
What is the average salinity of ocean water in parts per thousand
35 ppt
What happens to the pH of ocean water as more CO₂ dissolves?
The pH goes down (more acidic)
Name one way carbon moves from the ocean to the atmosphere.
When CO₂ is released from the water’s surface
How does hydrogen bonding affect water’s boiling point compared to other liquids?
It makes the boiling point higher
What tool is commonly used to measure seawater salinity?
A hydrometer or refractometer
How does evaporation affect the chemical composition of seawater?
It increases salinity
How does acidification affect shell-building organisms like coral or clams?
It makes it harder to build shells
How do marine organisms store carbon in the long term?
In shells and skeletons
What property of water allows it to move upward in plant stems through capillary action?
Cohesion and adhesion
Describe how the thermocline forms in the ocean.
It’s a layer where temperature drops quickly with depth
How do gases like oxygen and carbon dioxide enter and leave the ocean?
Through exchange with the atmosphere
What chemical forms when CO₂ reacts with seawater?
Carbonic acid (H₂CO₃)
What’s the difference between short-term and long-term carbon cycles?
Short-term happens fast, long-term takes millions of years
How does water’s density change as it freezes and why is this important for aquatic life?
Ice is less dense and floats, keeping water below from freezing
Explain how salinity and temperature together create ocean layering (stratification).
Warm, less salty water stays on top of cold, salty water
What is the “principle of constant proportions”?
The ratio of ions in seawater stays the same everywhere
How might ocean acidification disrupt marine food webs?
It harms small shell organisms that larger animals eat
How are humans changing the ocean carbon cycle?
By burning fossil fuels and adding extra CO₂ to the air and sea