Thermodynamic properties

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Corresponding extensive and intensive thermodynamic properties
Extensive
property
Symbol SI units Intensive
property**
Symbol SI units
Volume
V
m3 or l*
Specific volume***
v
m3/kg or l*/kg
Internal energy
U
Joule
Specific internal energy
u
Joule/kg
Entropy
S
Joule/K
Specific entropy
s
Joule/(kg·K)
Enthalpy
H
Joule
Specific enthalpy
h
Joule/kg
Gibbs free energy
G
Joule
Specific Gibbs free energy
g
Joule/kg
Heat capacity
at constant volume
CV
Joule/K
Specific heat capacity
at constant volume
cv
Joule/(kg·K)
Heat capacity
at constant pressure
CP
Joule/K
Specific heat capacity
at constant pressure
cP
Joule/(kg·K)

Halochromism in chromophores

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Halochromism occurs when a substance changes color as the pH changes. This is a property of pH indicators, whose molecular structure changes upon certain changes in the surrounding pH. This change in structure affects a chromophore in the pH indicator molecule. For example, phenolphthalein is a pH indicator whose structure changes as pH changes as shown in the following table:

Structure    
pH 0−8.2 8.2−12.0
Conditions acidic or near-neutral basic
Color name
colorless
pink to fuchsia
Color

In a pH range of about 0-8, the molecule has three aromatic rings all bonded to a tetrahedral sp3 hybridized carbon atom in the middle which does not make the π-bonding in the aromatic rings conjugate. Because of their limited extent, the aromatic rings only absorb light in the ultraviolet region, and so the compound appears colorless in the 0-8 pH range. However as the pH increases beyond 8.2, that central carbon becomes part of a double bond becoming sp2 hybridized and leaving a p orbital to overlap with the π-bonding in the rings. This makes the three rings conjugate together to form an extended chromophore absorbing longer wavelength visible light to show a fuchsia color.[1] At pH ranges outside 0-12, other molecular structure changes result in other color changes; see Phenolphthalein for details.

Variables

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Conjugate variables
p Pressure
V Volume
T Temperature
S Entropy
µ Chemical potential
N Particle number
Thermodynamic potentials
U Internal energy
A Helmholtz free energy
H Enthalpy
G Gibbs free energy
Material properties
? Density
CV Heat capacity (constant volume)
CP Heat capacity (constant pressure)
ßT Isothermal compressibility
ßS Adiabatic compressibility
a Coefficient of thermal expansion
Other conventional variables
  Work done by the system on its surroundings
  Heat transferred from the surroundings into the system
Constants
kB Boltzmann constant
R Ideal gas constant

Lenin vs. Gorky in Capri, Italy in 1908
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40. White to move - White resigns

White threatens with the following rook sacrifice leading to mate:

40. .......... Rh1+
41. Kxh1 Qh2#.

In the diagram at right with white to move next, black is threatening with the following rook sacrifice leading to mate.

40. ........ Rh1+
41. Kxh1 Qh2#

The pawn on g2 cannot take the rook on h3 because the queen on g3 is pinning it with a vertical line of attack. The only move to prevent the above moves is 40. Nf4 which temporarily blocks black's bishop from protecting his queen, but to no avail. The black bishop can take the knight by 40. ..... Bxf4 renewing the same threat of mate in 2 or Black can respond as follows to mate anyway:

40. Nf4 Qh2+
41. Kf 2 R/h3xf 3#

In this case, white could not take the mating rook now on f 3 with the g2 pawn because the queen on h2 would now be pinning it with a horizontal line of attack.










For =Tabular iceberg= article

Antarctic icebergs formed by breaking off from an ice shelf, such as the Ross Ice Shelf or Ronne Ice Shelf, are typically tabular. The largest icebergs in the world are formed this way.


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White to move - What sacrifice move should white make ?

Example: In the diagram at right with white to move next, what sacrifice move should white make ?

Answer: Force a bishop sacrifice by moving the white bishop on f 5 to g6 with check. The only way for black to get out of check is to take the checking bishop with black's pawn on h7. White follows with queen retakes pawn on g6 producing checkmate.

White can force mate in 2 in the diagram at right as follows.
1. Bg6+ h7xg6
2. Qxg6 #









Energy level

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for Gas leak article

For example, a natural gas leak caused an explosion destroying a school in New London, Texas in 1937, killing about 300 (or more) students and teachers.[2]

  1. ^ UV-Visible Absorption Spectra
  2. ^ Texas State Historical Commission. "New London School Explosion". StoppingPoints.com.

Theory of Ultraviolet-Visible (UV-Vis) Spectroscopy

 
Energy levels for an electron in an atom: ground state and excited states. After absorbing energy, an electron may jump from the ground state to a higher energy excited state.

∞I

R


Comparison of butane isomer boiling points
Common name n-butane isobutane
IUPAC name butane 2-methylpropane
Molecular
form
   
Boiling
Point (°C)
–0.5 –11.7


Comparison of pentane isomer boiling points
Common name n-pentane isopentane neopentane
IUPAC name pentane 2-methylbutane 2,2-dimethylpropane
Molecular
form
     
Boiling
Point (°C)
36.0 27.7 9.5

Table of compounds

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Compounds in graph of molar mass vs. boiling point
Alkanes Chloroalkanes Alkenes Alcohols Aldehydes Ketones Carb. acids Ethers
n-propane chloromethane propene methanol methanal propanone methanoic acid methoxymethane
n-butane chloroethane 1-butene ethanol ethanal butanone ethanoic acid methoxyethane
n-pentane 1-chloropropane 1-pentene 1-propanol propanal 2-pentanone propanic acid ethoxyethane
n-hexane 1-chlorobutane 1-hexene 1-butanol butanal 2-hexanone butanoic acid 1-ethoxypropane
n-heptane 1-chloropentane 1-heptene 1-pentanol pentanal 2-heptanone pentanoic acid 1-propoxypropane
n-octane 1-chlorohexane 1-octene 1-hexanol hexanal hexanoic acic

Refueling and Overhaul

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US Navy submarine in drydock filled with seawater.
 
Submarine in drydock drained of seawater at a shipyard. Note blocks (in dark shadow) under the hull.
Typical back-rank mate position
From Burgess, p. 16
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White wins with 1.Rd8#
Another back-rank mate position
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White wins with 1.Rd8#
Same back-rank mate position
but with blocking knight
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White wins with 1.Rd8+ Nf8 2.Rxf8#
If the knight is unprotected at f8, its check block is futile, merely delaying mate by a move.
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Black to move - Can black avoid back rank mate by moving his b pawn to make luft at b7 and attacking the white knight?
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White to move - White can checkmate with a queen sacrifice (taking knight) as follows:

1. Q-h7+  K-f8
2. Q-h8+  Nxh8
3. Rxh8#

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White to move[1] - How can white get rid of black's extra rook advantage in this game?

Example: In this example position, white's pawn on c5 is in position to capture black's queen except that it is pinned along its 5th rank, blocking black's rook on e5 from capturing white's queen; an immediate capture by the c5 pawn would result in an even exchange of queens. However, white's queen can move out of that rank by checking with Qa6+, forcing black to get out of check on the following move and simultaneously unpinning white's c5 pawn, allowing it to capture the black queen on white's next move by cxd6.

Blind swine mate

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White to move and mate in 3 moves.
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White has just checkmated after 3 moves.

The name of this pattern is attributed to Polish master Dawid Janowski referring to coupled rooks on a player's 7th rank as swine.[2] In the first partial position at right and assuming there are no interferences, white can force checkmate as follows:

  1. Rxg7+ Kh8
  2. Rxh7+ Kg8
  3. Rbxg7#

For this type of mate, the rooks on white's 7th rank can start out on any two of the files from a to e, and although black pawns are commonly present as shown, they are not really necessary to effect the mate. The rightmost diagram shows the corresponding partial position after white checkmates according to the preceding moves listed.

  1. ^ Shredder Computer Chess - Medium problem on 1/21/2016
  2. ^ MacEnulty, David, The Chess Kid's Book of Checkmate, chap. 21 - The Blind Swine Checkmate, pp. 29-30, Random House Puzzles & Games, 2004, ISBN 0812935942, 9780812935943