UNIT 3: Chapter 5. The Chemistry of Seawater

Rank the gases present in the ocean according to their abundance (percent by volume), with the most abundant on top.

1.) Nitrogen 2.) Oxygen 3.) Carbon Dioxide

About ______ percent of the weight of seawater is dissolved salts.

3.5

What is a buffer?

A substance that prevents drastic changes in the pH of a solution

A charged atom, group of atoms, or molecules is called a(n)_________ . Positively charged examples are called __________ and negatively charged examples are ________.

Blank 1: ion Blank 2: cations Blank 3: anions

The most abundant dissolved gases present in the ocean are ______ ,_____ , and carbon dioxide.

Blank 1: oxygen or O Blank 2: nitrogen or N

The most abundant dissolved gases present in the ocean are _______, _____, and carbon dioxide.

Blank 1: oxygen or O Blank 2: nitrogen or N

Dissolved constituent concentrations in water are expressed in terms of_______ , _______ , and molarity.

Blank 1: weight Blank 2: volume

In warm climates, salt in seawater is concentrated using evaporation and then extracted for use. How is salt recovered in cold climates?

By allowing the water to freeze and then collecting the leftover brine

How are concentrations of oxygen in seawater measured directly?

By using a probe that sends an electronic signal back to a receiver on a ship or buoy

Match the type of ocean salt ion to its original source

Cations Earth's crust Anions Earth's mantle

Rank the major constituents of seawater according to their abundance by weight, with the highest weight at the top and the lowest weight at the bottom. Instructions

Chloride, Sodium, Sulfate, Magnesium, Calcium, Potassium.

What is desalination?

Creating fresh water from salt water

What is the general name of the process used to obtain fresh water from salt water?

Desalination

The cations found in seawater originally came from ______, whereas the anions originated from ______.

Earth's crust; Earth's mantle

What process is used to concentrate the salt content of seawater in order to extract halite for use as table salt?

Evaporation in shallow ponds

True or false: Water solutions contain only H2O molecules.

False

Anthropogenic carbon dioxide concentrations in the atmosphere have ______ over the past 150 years.

Increased

What happens to the approximately 300 million metric tons of excess oxygen produced each year by photosynthetic marine organisms?

It is incorporated into sediments and then eventually formed into rocks.

What happens to oxygen produced by photosynthetic marine organism? (Select all that apply.)

It is incorporated into sediments and then eventually formed into rocks. It is consumed by bacteria.

Select the three important nutrients needed for the growth of marine life (i.e., plants, phytoplankton, and diatoms).

Nitrogen Phosphorus Silicate

Match the term to the correct description.

Osmosis - The movement of water across a semipermeable membraneReverse osmosis - the forcing of water movement through a semipermeable membrane using pressure

Nitrogen, ______ , and silicate are important to different forms of marine life for growth, as they act like the fertilizers of the ocean. These ions are present in very low concentrations in seawater.

Phosphorus

What is the name given to the mean time that a substance remains in the ocean before moving on to another part of the hydrologic cycle?

Residence time

Which of the following are the six major constituents of seawater? (Select all that apply.)

Sulfate Potassium Magnesium Calcium Chloride Sodium

What happens to the organic substances present in seawater? (Choose all that apply.)

They are used by organisms. They are broken down into smaller particles. They accumulate in sediments.

Match the way in which dissolved constituent concentrations in water are expressed with its scientific unit.

Weight - mg/kgVolume - mg/lMolar terms - moles/kg

You use a salinometer to measure the salinity of two water samples, and the results show that Sample A has a higher conductivity than Sample B. Can you assume that Sample A has a higher salinity?

Yes, because the more ions in the form of dissolved salts available, the more conductive the liquid.

Photosynthesis in the ocean results in the addition of CO2 into intermediate and deep-ocean water when organisms sink and decay through a process called the _______ pump.

biological

The process by which CO2 (and then carbon) is added to intermediate and deep-ocean water and the ocean bottom, through the involvement of photosynthetic organisms, is called the ______.

biological pump

Water solutions contain ______.

both H2O molecules and H+ and OH- ions

A substance that acts to prevent the sudden change of pH in a solution is called a(n

buffer

By measuring the pH of seawater, one can indirectly determine the water's ______ concentration.

carbon dioxide

A salinometer measures the salinity of ocean water by measuring ______.

electrical conductivity

Marine plants undergo photosynthesis in the lighted portion of the ocean called the ______ zone.

euphotic

The ______ zone is shallow in coastal waters but may extend to 200 meters in the open ocean where there are fewer suspended particles and sunlight can reach greater depths.

euphotic or photic

Match the term to its correct definition.

ion: charged atom or moleculecation: positively charged atom or moleculeanion: negatively charged atom or molecule

The ______ present in seawater include proteins, carbohydrates, and fats.

organics

Marine plants undergoing photosynthesis produce and release ______ into seawater.

oxygen

Organisms undergoing respiration remove ______ from seawater and produce and release carbon dioxide.

oxygen

What dissolved gas do heterotrophic organisms take up from seawater in order to respire?

oxygen or O2

Marine plants take up carbon dioxide from seawater in order to . (Use only one word per blank.)

photosynthesize

The relative ______ of major seawater constituents remain the same for different geographic locations and water depths.

ratios

The relative ratios of major seawater constituents ______.

remain the same, regardless of depth or geographic location

The average time a substance remains in the ocean (or any specific part of the hydrologic cycle) is called its time.

residence

Osmosis is the movement of water across a semipermeable membrane, whereas osmosis uses pressure to force the movement of water across a membrane.

reverse

The ______ of the oceans has remained relatively constant over time because the input of salts is equal to the output.

salinity

The ocean contains an average of 35 parts per thousand dissolved salt; this is the ocean's ______.

salinity

The concentration of CO2 in the atmosphere has increased over the last 150 years primarily due to ______.

the burning of fossil fuels and deforestation

In order for the salinity of the oceans to have remained the same over the past 1.5 billion years, the input of salts into the ocean needs to equal ______.

the output