Water and Seawater

Practice flashcards for the lecture on Water and Seawater covering molecular properties, salinity, thermal properties, and density.

What is the molecular composition of water (H2O)?

One oxygen atom and two hydrogen atoms bonded by sharing electrons.

What shape does the H2O molecule take due to its dipolar nature?

Both hydrogen atoms are on the same side of the oxygen atom, resulting in a bent shape.

What is hydrogen bonding in water?

Attraction between the small positive charge at the hydrogen end and the small negative charge at the oxygen end of water molecules.

What properties result from hydrogen bonding in water?

High surface tension, high solubility of chemical compounds, and unusual thermal properties.

Why is water considered the universal solvent?

Water can dissolve nearly everything due to its polarity.

At what temperatures does water melt and boil under normal conditions?

Water melts at 0°C and boils at 100°C.

What is a calorie in the context of water?

The amount of heat needed to raise the temperature of 1 gram of water by 1°C.

What unusual thermal property does water possess?

Water has a high heat capacity, meaning it can absorb and release a lot of heat without a significant change in temperature.

How does salinity affect the density of seawater?

Density increases as salinity increases.

What is the typical salinity of seawater?

3.5% or 35 parts per thousand (‰).

What is the halocline?

A layer where salinity changes rapidly with depth.

How does temperature affect the density of water?

Density of water increases as temperature decreases.

What effect does increased salinity have on the freezing point of seawater?

Higher salinity lowers the freezing point of seawater.

What is the relationship between temperature, salinity, and density in seawater?

Two samples can have the same density with different combinations of temperature and salinity.

What ion is primarily responsible for the alkalinity of seawater?

Bicarbonate ions (HCO3-).

What role do gases play in seawater?

Oxygen is high at the surface due to photosynthesis; carbon dioxide increases with depth.

What is the role of carbonate buffering in seawater?

It helps maintain stable pH levels in ocean waters.

What is the significance of the 'steady state ocean'?

The ocean is in chemical equilibrium with constant proportions of dissolved solids.

What is the average residence time of sodium ions (Na+) in the ocean?

260 million years.

What does evaporation do to the salinity of seawater?

It increases the salinity by removing water while leaving salts behind.

How does melting sea ice affect seawater salinity?

It adds fresh water, decreasing seawater salinity.

What effect does precipitation have on ocean salinity?

It adds fresh water, leading to lower salinity.

What is the density of seawater?

It typically varies between 1.022 and 1.030 g/cm³.

What are the primary ways to measure salinity?

Evaporation, chemical analysis, and electrical conductivity.

What temperature range does surface ocean salinity vary?

Generally between 33 and 38 parts per thousand (‰).

What is unique about the density of ice compared to liquid water?

Ice is less dense than liquid water.

What is the functional importance of the pycnocline in the ocean?

It corresponds to a zone where density increases rapidly with depth.

What are high latent heats of water important for?

They affect evaporation/condensation and melting/freezing processes.

What is the significance of high latent heat during state changes in water?

It requires additional heat to overcome hydrogen bonds during melting and vaporization.

How does global temperature regulation relate to oceans?

Oceans moderate temperature changes and transport surplus heat.