Review Of The Chem Quizzes

Question 1

3.5 billion years ago, single cells called ________ evolved, which invented a way to transduce solar energy into energy that could be stored in the form of a carbon-carbon bond. The chemical reaction that these organisms carried out is referred to as ___________ and produced _________ as a waste product. This product is toxic to anaerobic organisms that lived in the ocean at the time

Answer 1

Cyanobacteria

Photosynthesis

O2

Question 2

To explain how the first snowball earth disappeared, it is believed that ______ played an important role because they released massive amounts of _______, which is an important _______.

Answer 2

Volcanoes

CO2

Greenhouse gas

Question 3

Soon after the O2 concentration in the atmosphere reached present concentrations, photochemical process resulted in the formation of ______ in the atmospheric layer, which is referred to as the _______. This is important because this gas absorbs solar radiation in the ____ range, which protects organisms like sheep from forming cataracts.

Answer 3

O3

Stratosphere

200-300nm

Question 4

the emission of man-made greenhouse gases into the troposphere will absorb/redirect the outgoing infrared radiation from Earth and thus result in a _________ radiative forcing. Conversely, the introduction of volcanic ash into the stratosphere would result in a __________ in incoming solar radiation and therefore correspond to a _________ radiative forcing

Answer 4

Positive

decrease

negative

Question 5

the chemistry that forms the basis for the foundation of the ozone hole in the Antarctic involves converting two inactive forms of chlorine; ____ and _____ to CL2 on the surface of particles within polar stratospheric clouds. In the antarctic spring, a photochemical reaction will then convert this molecule to CL which will destroy massive amounts of O3 molecules according to _____________ (name mechanism)

Answer 5

HCl

ClONO2

mechanism II

Question 6

The mechanism I of O3 destruction relies on ____ for the completion of the catalytic cycle and is therefore rather sluggish in the lower stratosphere. It follows the net overall reaction of: _______

Answer 6

oxygen radicals

O3 + O –> 2O2

Question 7

although stratospheric O3 has been destroyed by natural compound catalysts that entered this atmospheric layer (e.g. CH3Cl emitted from the oceans) for millennia, this was eventually overshadowed by the massive release of man-made ____ into the atmosphere (1,000,000 t in 1980), which resulted in the formation of much larger quantities of inactive forms of chlorine

Answer 7

chlorofluorocarbons

Question 8

the melting of the entire Greenland ice shelf (triggered by global warming) is dangerous because it would decrease the _____ of the seawater off the coast of Newfoundland/Greenland. this in turn would bring the _____ to a halt and is likely to cause the northern hemisphere to slip into the next ice age because heat will no longer dissipate to the polar regions but ocean currents

Answer 8

salinity

oceanic conveyer

Question 9

molecular hydrogen (H2) is present in the atmosphere at an average concentration of 0.5 ppm. Since it is a homonuclear diatomic molecule, it isn’t associated with _______ and is therefore not a _____ gas.

Answer 9

dipole moment

greenhouse gas

Question 10

Some scientists have suggested addressing climate change/global warming by an approach referred to as ‘CO2 sequestration.’ Briefly explain what this approach would consequently entail. Provide two examples of what some scientists have proposed to actually achieve this and how long-term sequestration without harming the ecosystem can be practically accomplished

Answer 10

when CO2 is removed from the air and deposited in an underground or ocean location that would prevent its release into the air.

ex. 1 – CO2 could be sequestered by burial in deep ocean waters, where it would dissolve, or in very deep aquifers under land or the seas, or in empty oil and natural gas wells or coal seams

ex. 2 – also planting more trees

Question 11

in automobile exhausts, the most relevant pollutant gases from an environmental chemistry point of view are: ___, ____ and _______, which can be removed by ______. Nitric oxide, for example, is converted to innocuous gases following the chemical reaction: ______.

Answer 11

CO

NO

unburnt hydrocarbons

catalytic converters

2NO –> N2 +O2

Question 12

_____ (DMS) is a gas that is naturally emitted from the ocean, and plays an important role in atmospheric chemistry. In the troposphere, it can be converted to ___, which can then diffuse into the stratosphere where it will be converted to ___, which results in the formation of ___. the latter will reflect incoming solar radiation to space and thus play a role in solar radiation management.

Answer 12

CH3-S-CH3 (dimethyl sulfide)

SO2

H2SO4

sulfate layer

Question 13

the mortality rate of humans is most strongly correlated with the air quality parameter _____ because these ____ particles have a ____, which facilitates the transfer of carcinogens to lung cells.

Answer 13

PM2.5

respirable

large surface area

Question 14

imagine that the analysis of aerosol particles has revealed a substantial fraction to be compared of NH4HSO4. Based on this chemical composition, there particles are classified as a ____ because their formation can be explained by the chemical reaction of _____, most likely emitted from agriculture

Answer 14

secondary aerosol

gaseous NH3

Question 15

particulates in the air with a diameter of 0.01 um are referred to as ____. They are important in the context of atmospheric science because they are involved in the formation of ____.

Answer 15

Aitken nuclei

clouds

Question 16

one of the 12 green chemistry principles states that the raw material feedstock that is used for the synthesis of a consumer product should not be _____, but rather ______. An example is the production of succinic acid which is increasingly produced from biobased materials instead of fossil fuels (e.g. oil)

Answer 16

depleting

renewable

Question 17

one way to significantly reduce the amount of chemical waste that is produced worldwide every year from the synthesis of chemicals (e.g. ibuprofen) is to increase the ___————- of the chemical reactions that are used for their synthesis

Answer 17

atom efficiency

Question 18

the reason why water is such an excellent solvent for many substances is the fact it can undergo _______ with certain functional groups of these substances

Answer 18

hydrogen bonding

Question 19

the growth of plankton in the top layer of the oceans is fuelled by an endless source if carbon from the air but is inherently limited by the availability of _____+______. Some scientists executed so-called ‘ocean fertilization’ experiments, which increased the growth of phytoplankton at the surface of the ocean. hen the dead cells sink to the ocean the CO2 that was absorbed by the cells would then be sequestered in the deep ocean. this is an example which illustrates the importance of the concept of -_______.

Answer 19

Fe

Zn

global biogeochemical cycles

Question 20

one physicochemical parameter that distinguishes water from many other solvents is the fact that its density decreases when it freezes. this can be explained by the ______ of hexagonal ice, the most important form from an environmental chemistry viewpoint

Answer 20

open structure

Question 21

what is the PM index and what is its unit of measure?
the typical PM2.5 index in an urban setting is 1-5, while the corresponding PM 10 index is about 20-30. Which one of these indices is more relevant from a public health point of view (provide two reasons why)

Answer 21

PM index is the amount of particulate matter (in ug/m^3) present in the atmosphere and shows the health risk it poses to humans

Pm2.5 is more relevant from a health point of view as it doesn’t settle out of the air as fast as PM10 (strokes law). it also is small enough to go unfiltered by the nose and throat and penetrate deep into the blood and lungs.

Question 22

the microbially-mediated redox reaction CH2O +O2 –> CO2 + H2O occurs in surface waters (e.g. rivers). it is referred to as ____ and involves the ____ of carbon. Because this chemical reaction (from left to right) is fast compared to the much slower _____ from the air in stagnant bodies of water (lakes and ponds), the extent of oxidizable pollution (i.e. CH2O) in surface waters is expressed by its _____. the latter refers to the ______ that is needed to oxidize the oxidizable pollution (e.g. dry leaf litter) that is present in I litre of water

Answer 22

respiration
oxidation
dissolution of O2
biological oxygen demand
mg of O2

Question 23

to locate the point source of a pollution event that involves an oxidizable matter in a river (e.g. sewage influx), it is useful to determine the _____ along the river. This will ____ below the point source, which is referred to as the _____ and can result in ____.

Answer 23

dissolved O2 concentration
gradually decrease
decomposition zone
fish kills

Question 24

the measurement of the diurnal cycling water quality parameters at Pine Creek revealed that the pH increases from ~8.0 at sunrise to ~9.0 at sunset. The root cause for this increase is _____, which is associated with the removal of _____ based on the chemical equilibrium reaction _____

Answer 24

photosynthesis
H3O+
CO2 + H2O <—> H+ + HCO3-

Question 25

a DNAPL is classified as a liquid with a density of _____. In the case of an underground storage tank, the spill will therefore ____.

Answer 25

>1.0 g/ml percolate down to bedrock

Question 26

the determination of the log Kow value of any environmental chemical is useful as it allows us to predict to what extent it will tend to _______ in organisms. For any given structure of a pesticide, the introduction of functional grounds with aromatic groups will result in a ____ of its low Kow value.

Answer 26

bioaccumulate increase

Question 27

in terms of the changes that soil will undergo after it has received acid rain over the months, it is important to understand that the _____ will not change, but that its ____ will _____.

Answer 27

cation exchange capacity base saturation decrease

Question 28

nutrient loss from soil to groundwater is a big agricultural problem. In this context, it is important to be aware of the fact that the loss of Ca and Mg from any given soil is prevented 'chemically; by the soil's _______ and 'physically through their ____.

Answer 28

Cation exhange capacity plant root uptake

Question 29

humic matter refers to the complex chemical molecules that are present in any soil that is the result of the physical breakdown of plant leaves filled by its _____ in the first 10-15cm of any soil.

Answer 29

microbial decomposition

Question 30

what is the cation exchange capacity of soil? explain where soils with a higher cation exchange capacity are better able to achieve good agricultural productivity than those with comparatively low cation exchange capacities. name the component in soil that contributes to having a high CEC and draw a simple scheme which explains how metals bind.

Answer 30

describes a soil`s ability to hold and exchange cations. It is a relative reflection of a soil's ability to hold nutients influencing soil structure stability, nutrient availability, soil pH and the soil's reaction to fertilisers and other ameliorants. a useful indicator of soil fertility Humus, the end product of decomposed organic matter, has the highest CEC value because organic matter colloids have large quantities of negative charges. Humus has a CEC two to five times greater than montmorillonite clay and up to 30 times greater than kaolinite clay, so is very important in improving soil fertility.

Question 31

to disinfect drinking water, Cl2 gas (oxidation state 0) is often bubbled through, which will result in the formation of Cl- as well as ____. since the latter molecular reaction product is _____ changed, it will easily diffuse through the cell wall of pathogens, which as ____ and kill them. If natural organic matter is present in the water that is being treated with Cl2, however, this 'chlorination' will inevitably result in the formation of ____, the presence of which has been shown to increase the risk of ____.

Answer 31

HOCl neutrally giardia lamblia disinfection byproducts bladder cancer

Question 32

in the conventional wastewater treatment process primary treatment refers to the removal of ____, while secondary treatment involves the significant decrease of the waters ____.

Answer 32

physical objects BOD

Question 33

the excessive use of fertilizers in agriculture and results in the inadvertent release of highly water-soluble _____ to the groundwater, which -- if the after is consumed 00 can cause an adverse health effect which is called _____.

Answer 33

nirtate blue baby syntrome

Question 34

a potentially toxic compound/chemical can only exert a toxic effect if it is ____ across the cell membrane. In principle, this translocation can happen either in the ____ or across the ____ (i.e. in the application of cream in the _____.

Answer 34

absorbed ? skin intestine

Question 35

if the LD50 of compound A is 50 mg/kg and compound B is 5mg/kg, the former compound is ___ acutely toxic than the latter compound

Answer 35

less

Question 36

for many years, one of the most common diseases for farmers was _____, which was caused by manually spraying the pesticide onto the crop. this is an example of _____ exposure

Answer 36

lip cancer occupational

Question 37

for there to be a toxicological problem there must be a chemical hazard (i.e. a toxin), a ____ and most importantly, an _____. an example of an exerting toxicological problem is the potentially fatal exposure of children to ____, which is contained in which ____.

Answer 37

exposure pathway receptor organism cadmium jewelry

Question 38

the determination of the LD50 value for the environmental or occupational chemical today is less relevant because the biggest problem today is the ____ explore (not environmental or occupational) to potentially toxic chemicals

Answer 38

chronic

Question 39

the Ld50 of any chemical that has been determined with any animal model is not an accurate number because the route of ____ significantly affects the number/ outcome of any experimental involving animals

Answer 39

administration

Question 40

someone has ingested benzoic acid, which contains a carboxylic acid (pKa = 4.2). explain whether this I compound will be absorbed into the bloodstream from the stomach (pH=2.0)or from the intestine (intestinal juice pH 6.0) and why. what is the sane if teg mechanism by which this compound is absorbed into the bloodstream?

Answer 40

will be protonated/ neutral at pH 2 by passive diffusion stomach