APES Chemistry Review
Basics
→ Neutrons, protons, and electrons are the components of atoms, which combine to form molecules.
→ The basic unit of all chemical compounds, whether natural or man-made, is the molecule.
Abbreviations
C ≡ carbon S ≡ sulfur U ≡ uranium Cl
2
≡ chlorine
O
2
≡ oxygen N
2
≡ nitrogen H
2
≡ hydrogen P ≡ phosphorus
NO
2-1
≡ nitrite NO
3-1
≡ nitrate SO
4-2
≡ sulfate NH
3
≡ ammonia
NO
x
≡ oxides of nitrogen or nitrogen oxides (NO, NO
2
)
SO
x
≡ oxides of sulfur or sulfur oxides (SO
2
, SO
3
)
VOC ≡ volatile organic compounds (compounds containing carbon which readily evaporate, ex. methane, benzene)
PAN ≡ peroxyacyl nitrates
pH
→ pH is the negative log of the hydrogen ion concentration (sometimes called the potential of hydrogen ion).
→ Mathematically it is represented by the equation: pH = –log[H
+
] or pH = –log[H
3
O
+
]
→ [H
+
] is the molarity (# of moles per liter) of H
+
ions
→ [H
+
] and [H
3
O
+
] are essentially the same. H
3
O
+
is called the hydronium ion, it results when H
+
are in water.
→ Low pH corresponds to being more acidic. High pH corresponds to being more basic.
→ The opposite of acidic is basic.
→ The range of pH is from 0 to 14.
pH=1 ∴ [H
+
]=1 x 10
-1
moles/liter (very acidic) pH=4 ∴ [H
+
]=1 x 10
-4
moles/liter (acidic)
pH=6 ∴ [H
+
]=1 x 10
-6
moles/liter (slightly acidic) pH=7 ∴ [H
+
]=1 x 10
-7
moles/liter (neutral)
pH=8 ∴ [H
+
]=1 x 10
-8
moles/liter (slightly basic) pH = 13 ∴ [H
+
]=1 x 10
-13
moles/liter (very basic)
Nuclear Fission
→ Nuclear fission (splitting atoms) is the source of energy in today’s nuclear power plants. The reactions used are chain reactions, in
which one neutron initiates the reaction of millions of Uranium nuclei.
1 U-235 + 1 n → 1 Kr-92 + 1 Ba-141 + 3 n + energy (the 3 neutrons (n) initiate further reactions)
3 U-235 + 3 n → 3 Kr-92 + 3 Ba-141 + 9 n + energy (the 9 neutrons initiate further reactions)
9 U-235 + 9 n → 9 Kr-92 + 9 Ba-141 + 27 n + energy (the 27 neutrons initiate further reactions)
This continues until there are millions of neutrons being produced and millions of times more energy, as well.
→ A moderator and control rods are used to absorb neutrons to prevent the chain reaction from getting out of control which would
result in a meltdown.
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