Ch.6 Marine Science

What are adhesion and cohesion? How are they similar and different?

Adhesion is when water molecules stick to other water molecules. Cohesion is when water molecules stick to other surfaces. These are both properties of water. Cohesion creates surface tension while Adhesion causes spreading of water.

How does cohesion make water droplets round?

Cohesion is a property of water and one of the characteristics of cohesion is surface tension. This allows cohesion to make round water droplets instead of making them lay flat.

What is surface tension and how can it be reduced?

Surface tension is a property of Cohesion when water molecules or liquid molecules interact with a surface, they form a round shape. Raising the temperature or mixing in a solute to the water molecule can reduce the surface tension.

How does fresh water differ from seawater in regards to boiling point, freezing point and heat capacity?

Seawater has a higher boiling point since the salt ions are dissolved in the water allowing the bonds between the salt and the water to trap the heat and gas. Fresh water has a higher heat capacity since it is less dense than seawater. Seawater’s salt ions form bonds with the water molecules which reduces the amount of free hydrogen bonds that can absorb the energy. Fresh water also has a higher freezing point than seawater because the salt ions in seawater make it hard for the water molecules to form ice crystals.

Compare/contrast how closely water molecules are packed together in hot water versus cold water and in ice versus liquid water.

In hot water, water molecules are spread out because they are absorbing the energy and when heat is added, the molecules expand. However, cold water molecules are packed tightly since there is no heat energy spreading the molecules out. Liquid water molecules are somewhere in between cold and hot water where the molecules are spread evenly and not too tightly packed or spread out.

What is a polar molecule? Give an example and sketch how polar molecules interact with each other.

A polar molecule is a molecule that is attracted to opposite charges such as a water molecule. Water is always polar because of it’s hydrogen bonds.        

Why are the oceans salty? What are some ways salt is added to seawater?

Oceans are salty from erosion of mountains, volcanic eruptions, and hydrothermal vents.

What are the ways salt is removed from seawater?

Salt is removed from seawater also from hydrothermal vents, marine organisms, and seafloor sediments where salt chemically binds to sediments.

Why does the concentration stay constant instead of always increasing? What is that property called?

The concentration of salt stays constant because even though there are many processes that add salt to the ocean, rivers and other fresh water sources can connect and stream into the ocean, diluting the concentration. This property is called chemical equilibrium.

What is hydrogen bonding? How does it affect the properties of water?

Hydrogen bonding is a weak electrical attraction that occurs between positive hydrogen in one molecule and a negative atom in another. Hydrogen bonding causes a higher boiling point, high surface tension, and increases polarity.

How are osmoconformers and osmoregulators different from each other?

Osmoregulators are organisms that manage their body’s salt levels to balance out their salinity with the ocean. Osmoconformers have the same level of salinity as the ocean and regulate their body to match their surrounding environment.

What is osmosis?

Osmosis is the process of where water moves through a semipermeable membrane from an area with more water meaning the minerals are less dissolved to a place with less water and more dissolved minerals.