Unique Nature of Pure Water
What type of bond holds water molecules together?
Hydrogen bonds
What is salinity?
The total amount of dissolved salts in seawater.
What is pH a measure of?
The concentration of hydrogen ions in a solution.
What human activity increases CO₂ in the ocean?
Burning fossil fuels.
What is the carbon cycle?
The movement of carbon among Earth’s spheres (atmosphere, ocean, land, and living things).
Why is water called the “universal solvent”?
Because it dissolves more substances than any other liquid.
What two ions make up most of seawater’s salinity?
Sodium and chloride.
What is the average pH of seawater?
Answer: About 8.1 (slightly basic).
What happens to ocean pH as CO₂ levels increase?
It decreases (the ocean becomes more acidic).
How does photosynthesis affect the carbon cycle?
Plants take in CO₂ and convert it into oxygen and glucose.
How does water’s polarity affect its ability to dissolve ionic compounds?
The positive and negative ends of water attract ions and pull them apart.
How does temperature affect seawater density?
Colder water is denser than warm water
What causes the ocean to maintain a relatively stable pH?
The carbonate buffering system.
How does ocean acidification harm coral reefs?
It weakens or dissolves calcium carbonate skeletons.
How do oceans act as a carbon sink?
They absorb CO₂ from the atmosphere and store it.
Explain how hydrogen bonding affects water’s boiling point compared to other similar molecules.
Hydrogen bonds make it harder to separate molecules, raising the boiling point.
What is a thermocline?
A layer in the ocean where temperature changes rapidly with depth.
What happens when CO₂ dissolves in seawater?
It forms carbonic acid, which can lower the pH.
Why is ocean acidification often called the “other CO₂ problem”?
Because it’s caused by the same emissions as climate change but affects the ocean.
What role do marine organisms play in the carbon cycle?
They use carbon to build shells and skeletons, locking it away when they die.
Why is water’s density anomaly at 4°C important for aquatic life in cold climates?
Ice floats because it’s less dense than liquid water, insulating life below.
Describe how salinity and temperature together influence ocean layering.
Warm, less salty water stays near the surface; cold, salty water sinks, creating layers.
How do chemical properties of seawater affect shell-forming organisms?
Lower pH reduces carbonate ion availability, making it harder to build shells.
Explain the long-term ecological impact of ocean acidification on marine food webs.
It can disrupt base species like plankton and shellfish, affecting entire ecosystems.
How does human activity disrupt the natural carbon cycle balance?
By burning fossil fuels and deforestation, increasing CO₂ faster than it can be absorbed.