Unit 7 Reading Assignment

In a _____ bond, electrons are not shared equally, but are closer to the more electronegative atom.

polar covalent

The chlorine-containing chemicals (HClO, ClO-, and Cl2) that remain in the water after the chlorination step in the water treatment process are called _____ chlorine.

residual

BOD is a measure of the amount of dissolved _____ microorganisms use up as they decompose organic wastes found in water.

Oxygen

How long would it take for coral reefs to regenerate from the effects of ocean acidification?

Thousands of years

Al2(SO4)3 and Ca(OH)2

Flocculating agents

68% of fresh water

Glaciers, ice caps and snowfields

Which of the following options correctly describe molecular polarity? Select all that apply.

-A molecule that contains only nonpolar bonds is nonpolar. -A molecule that contains polar and nonpolar covalent bonds could be polar or nonpolar. -Overall molecular polarity depends on the geometry of a molecule.

Which of the following statements describe the drawbacks of using chlorine-containing chemicals in the water treatment process? Select all that apply.

-Chlorine-containing chemicals can themselves be toxic. -The taste and odor of residual chlorine is objectionable. -Chlorine can react with organic matter to form trihalomethanes (THMs).

Which of the following options correctly describe the water cycle? Select all that apply.

-Climate can affect the water cycle. -A drop of water in the ocean could one day end up in a lake.

Which of the following options correctly describe the processes that contribute to ocean acidification? (Select all that apply.)

-Dissolved CO2 reacts with H2O to form H2CO3. -Increased atmospheric CO2 leads to more CO2 dissolved in the ocean.

Which of the following options correctly describe electronegativity and its trends? Select all that apply.

-Electronegativity increases from left to right in the periodic table. -The higher the electronegativity value of an element, the more strongly it attracts bonding electrons to itself. -The element with the highest electronegativity is fluorine.

Which of the following options correctly compare the effect of acid precipitation on lakes in different geological surroundings? Select all that apply.

-Lakes in granite areas tend to have lower pH values than lakes in limestone regions. -Lakes in limestone regions have a higher acid-neutralizing capacity.

Which of the following options correctly describe the different sources of fresh water? Select all that apply.

-Surface water is found in lakes, streams, and rivers. -Sea water can be used as a source of water. -Groundwater is found in aquifers.

Which of the following options correctly describe and interpret the illustration? (Select all that apply.)

-The illustration depicts a polar covalent bond. -The electrons in the O-H bond are closer to O, giving it a partial negative charge.

If the sign δ- is used to mark an atom in a covalent bond, it means that _____. (Select all the options that complete the sentence correctly.)

-this atom is more electronegative -this atom has a partial negative charge -this atom has a higher electron density

Approximately how much water per day is required to support the lifestyle of the average U.S. citizen, according to the U.S. Geological Survey?

100 gallons

Approximately how many people on the Earth lack access to clean drinking water?

2,100,000,000

What percentage of water on Earth is fresh water?

3%

How many liters of water can a single LifeStraw purify?

4000 L

According to the World Health Organization estimates, approximately how many infants and children die each day due to contaminated water?

> 3000

According to the USGS, how much water per day is needed by the average U.S. citizen?

> 390 L

What are the consequences of a large amount of phosphates and nitrates in the water? Select all that apply.

Algal blooms Dead fish Oxygen depletion

Cl2, NaClO, or Ca(ClO)2

Antibacterial agents

30% of fresh water

Aquifers

1% of fresh water

Atmosphere

Correctly order the steps showing the effect of decreased ocean pH on marine organisms such as coral. Start with the first step at the top of the list.

CO2(aq) + H2O (l) --> H2CO3 (aq) H2CO3 (aq) --> H+(aq) +HCO3-(aq) H+(aq)+CO3^2+(aq) --> HCO3^2-(aq) CaCo3(s) --> Ca^2+(aq) + CO3^2-(aq)

Marine organisms such as mollusks, sea urchins, and coral have shells composed of _____ and these species are affected by the levels of _____ ion in seawater.

CaCO3; CO32-

Both ozone (O3) and UV radiation have been used as alternative disinfectants to chlorine-containing compounds in the water treatment process. However, _______ must be added to the water after either of these treatment methods in order to protect the water after it leaves the treatment site.

Cl2

Which of the following species play a role in maintaining the normal pH of seawater? (Select all that apply.)

H2CO3 CO32- HCO3-

Which of the following is the correct condensed molecular formula for water?

H2O

Which of the following are responsible for protecting coastlines from ocean waves while providing a habitat for a diverse range of aquatic life?

Coral reefs

Which techniques are used to desalinate water? Select all that apply.

Distillation Reverse osmosis

Which of the following options correctly describe the effect of pH on life in a lake or stream?

Fish begin to be affected when the pH of a lake or stream drops below 6.0. Some hardy aquatic species can survive at a pH of below 5.0. If the pH drops to 4.0, a lake is essentially a dead ecosystem.

In what way does increasing ocean acidity affect coral reefs?

Increasing acidity leads to a decrease in the amount of CO32- ion available to build coral reefs.

0.3% of fresh water

Lakes, swamps, rivers

Which of the following statements correctly describe LifeStraw? Choose all that apply.

LifeStraw is a pipe filter. LifeStraw removes most bacteria, viruses, and parasites from water.

Which of the following are possible negative consequences of ocean acidification? Select all that apply.

Loss of a variety of marine species Damage to coastlines Damage to coral reefs from storms

Which of the following molecules is polar?

NH3

The release of _______ gas causes acid rain through formation of nitric acid, HNO3.

NO2

Which of the following gases cause acid rain? (Select all that apply.)

NO2 SO3

What waste is present in sewage that makes it more complicated to treat than contaminants found in water in the water treatment process? Select all that apply.

Nitrate ions Organic compounds

97% of Earth's water

Oceans

Which of the following would represent an example of a tragedy of the commons? (Select all that apply.)

Overfishing a lake Dumping waste into a public lake

F-

Prevents tooth decay

What are methods used to remove ions from salt water?

Reverse osmosis Desalination Distillation

How does ocean acidification affect marine organisms such as coral?

The CaCO3 in coral dissolves to replace the CO32- ions used up by excess H+ ions.

Why are some lakes able to resist a decrease in pH when exposed to acidic precipitation and/or runoff?

The soils or rocks surrounding the lake may contain bases, which neutralize the acid.

Which of the following are alternative disinfectants to chlorine-containing compounds used in water treatment? Select all that apply.

UV radiation Ozone (O3)

Which of the following methods is being used by some sewage treatment plants to decrease the effect of releasing phosphates and nitrates into surface water?

Using wetland areas to capture nitrates and phosphates before the water is returned to the surface water.

What is potable water?

Water that is safe to drink and to cook with

The capacity of a lake or other body of water to resist a decrease in pH when exposed to acidic precipitation or runoff is called its _____ capacity.

acid-neutralizing

Normal seawater is slightly _____ with a pH of around _____.

basic; 8.2

Fresh water found in an aquifer is located:

below ground (ground water)

What is the shape of a water molecule?

bent

The ability of a covalently bonded atom to attract the shared electrons is called .

electronegativity

True or false: A chemical company inadvertently dumps toxic waste into a local river, which pollutes the water for residents of a nearby town. However, this is not considered a tragedy of the commons since the company did not do this intentionally.

false

A water ______ is an estimate (for an individual or nation) of the amount of water required to sustain the consumption of goods and services. Listen to the complete question

footprint

3% of Earth's water

fresh water

Which of the following bodies of water is/are included in the natural water cycle? Select all that apply.

glaciers lakes rivers sea ice

A low BOD is an indication of _____ quality water.

good

pH below 6.0

many fish disappear

pH below 5.0

most aquatic life disappears

pH = 6.5 or slightly higher

normal, healthy lake

pH of 4.0 or lower

the lake is essentially dead

Ocean acidification is correctly described as _____.

the lowering of ocean pH due to increased atmospheric CO2

An estimate of the water used to produce a particular product is known as a _______.

water footprint

Match the symbols correctly to describe the uneven charge distribution in any polar covalent bond.

δ+ --> marks the atom with the lower electronegativity δ- --> marks the atom with the higher electronegativity