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ENVI 7060 > L.4 - Chemistry > Flashcards

L.4 - Chemistry Flashcards

1
Q

Define environmental chemistry:

A

It is the study of composition, reactions, and characteristics of matter

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2
Q

Why do we care to learn about envi. chemistry?

A

because it influences the ultimate fate of many chemicals discharged to soil, air, and water

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3
Q

What are the fundamental properties that the chemical basis depend on?

A

1) Air pollution
2) Water pollution
3) Sustainability
4) Climate change
5) Water quality management
6) Air quality management
7) Solid waste management

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4
Q

A chemical system is in equilibrium when:

A

1) at steady state (doesn’t vary with time)
2) it is well mixed
3) there is no net flow of mass, heat, or species w/ the surroundings
4) the net rate of chemical reaction is zero

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5
Q

What is pH?

A

-log [H+] (minus log of the hydrogen ion activity)

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6
Q

Define activity:

A

it is the measure of the effective concentration of a species in a mixture

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7
Q

When is pH acidic and when is it alkaline (w/ examples)?

A

pH = 7 neutral (ex. pure water) also where [H+]=[OH-]
pH < 7 acidic (ex. coffee, acid rain)
pH > 7 alkaline (ex. baking soda, bleach)

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8
Q

What does pH affect?

A
  • solubility in metals
  • corrosiveness in water
  • other chemical reaction rates
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9
Q

Define molarity:

A

it is the number of moles of solvent dissolved in one litre of solution

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10
Q

What is the standard chemical reaction equation?

A

aA + bB <> cC + dD (reactants <> products)

(A,B,C,D: distinct molecular species)
(a,b,c,d: number of units of species participating in reaction)

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11
Q

What do these “[]” represent?

A

the activity of the species in mol/L (solid & water activity = 1)

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12
Q

What is the equilibrium constant for water at 25’C?

A

Kw=10^-14

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13
Q

What are some equilibrium constants used other than of water?

A

1) Air-Water: Henry’s constant “KH”
2) Acid-Base Chemistry: Acid Ka, Base Kb
3) Precipitation Dissolution: Solubility product “Ksp”

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14
Q

What is electroneutrality?

A

when the sum of cations = the sum of anions
[H+] = [OH-]

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15
Q

As temp. increases, pH…..?

A

decreases

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16
Q

In a solution who produces [H+] and who produces [OH-]?

A

acids produces [H+], base produces [OH-]

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17
Q

Wen is solid-liquid equilibrium reached?

A

when a solid dissolves into ionic compounds at the same rate that ionic components recombine into solid form

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18
Q

What does the degree of dissolution of air in water depend on?

A
  • temperature
  • water purity
  • constituents present
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19
Q

Define Alkalinity:

A

the measure of water’s capacity to neutralize acids (by removing [H+] ions)

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20
Q

Define Buffering Capacity:

A

ability of water to resist changes in pH when either acidic or alkaline material is added

21
Q

What is partitioning?

A

how much the dissolved contaminant will partition onto the soil grain (equal to the amount dissolved in water)

22
Q

Define Adsorption:

A

when particles stick to the surface of the soil grain

23
Q

Define Absorption:

A

when particles are absorbed into the soil grain

24
Q

What is Organic Chemistry?

A

chemistry of compounds with carbon

25
Q

What is Biochemistry?

A

chemistry of life

26
Q

What are the properties of Organic Compounds?

A

1) they are combustible
2) less soluble in water than inorganics
3) have a carbon atom as their main structural component
4) several organics have same formula but different isomers/properties
5) most organics serve as a source of food or bacteria

27
Q

Why can carbon form thousands of different compounds?

A

1) because it has four covalent bonds
2) its atoms can link together in variety of ways

28
Q

What are the major classifications of compunds?

A

1) Aliphatic
2) Aromatic
3) Heterocyclic

29
Q

What happens as the number of carbons increases?

A

1) volatility decreases
2) solubility decreases
3) biodegradability decreases

30
Q

What are three types of Aliphatic hydrocarbons?

A

1) Straight-Chain
2) Branched
3) Cyclic

31
Q

Define Isomers:

A

different compounds that have the same chemical formula (each would have different chemical properties)

32
Q

What are Saturated Compounds?

A
  • compounds with no double bonds
  • each carbon atom is attached to four other atoms
33
Q

What are Unsaturated Compounds?

A
  • compounds with double or triple bonds
  • molecule contains two or more carbons that are joined by double or triple bonds
34
Q

Define Aromatic Hydrocarbons:

A

hydrocarbons that have a six-carbon ring structure as a basic component (benzene ring)

35
Q

What are PAHs?

A

Polyaromatic Hydrocarbons/ Polycyclic Aromatic Hydrocarbons, chemicals that have two or more attached benzene rings

36
Q

What are Heterocyclic Compounds?

A

compounds with at least two different elements as part of a ring structure

37
Q

Define an Atom:

A

fundamental building block of elements

38
Q

Define an electron:

A

it is an elementary particle with negative electrical charge that surrounds the atoms positively charge nucleus

39
Q

Define a proton:

A
  • one of basic particles of atom
  • found in the nucleus and has positive charge
40
Q

Define neutron:

A
  • one of the basic particles of an atom
  • has no electrical charge
41
Q

Define Atomic weight:

A

total number of particles in an atom’s nucleus

42
Q

Define Isotopes:

A

adding or removing neutrons from an atom

43
Q

Define alpha radiation:

A

alpha particles that are a nucleus of helium (releases 2 protons and 2 neutrons)

44
Q

Define beta radiation:

A

beta particles are electrons from the nucleus of helium

45
Q

Define gamma radioactivity:

A

composed of electromagnetic rays

46
Q

What is a radon?

A

it emits alpha radiation and is from rock

47
Q

What is radioactive decay?

A

time required for half of the atoms to spontaneously transform or decay into other elements

48
Q

What are some radiation health effects?

A

1) electron excitation or ionization cause biological molecules to become unstable
2) leads to a series of chemical formations of new molecules that didn’t exist before
3) over time, organisms respond to the damaged molecules or new molecules

ENVI 7060 (8 decks)

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