User:H Padleckas/sandbox

Thermodynamic properties

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

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. At pH ranges outside 0-12, other molecular structure changes result in other color changes; see Phenolphthalein for details.

Variables

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

$W$	Work done by the system on its surroundings
$Q$	Heat transferred from the surroundings into the system

Constants

kB	Boltzmann constant
R	Ideal gas constant

---

Lenin vs. Gorky in Capri, Italy in 1908

	a	b	c	d	e	f	g	h
8									8
7									7
6									6
5									5
4									4
3									3
2									2
1									1
	a	b	c	d	e	f	g	h

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.

• 
  Tabular iceberg
• 
  Blue tabular iceberg
• 
  Satellite image of tabular Iceberg B-15 on January 2001. The world's largest iceberg in the 21st century; it covered about 11,000 square miles.
• 
  Arial picture of tabular Iceberg B-15A, which calved off of iceberg B-15.
• 
  Tabular iceberg
• 
  Iceberg with submerged portion clearly visible
• 
  The northern edge of the giant iceberg, B-15A, in the Ross Sea, Antarctica.
• 
  Tabular iceberg
• 
  Tabular iceberg

---

Chess sacrifice

	a	b	c	d	e	f	g	h
8									8
7									7
6									6
5									5
4									4
3									3
2									2
1									1
	a	b	c	d	e	f	g	h

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

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.

---

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

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

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.

Back-rank checkmate

Typical back-rank mate position From Burgess, p. 16 a b c d e f g h 8 8 7 7 6 6 5 5 4 4 3 3 2 2 1 1 a b c d e f g h White wins with 1.Rd8# Another back-rank mate position . a b c d e f g h 8 8 7 7 6 6 5 5 4 4 3 3 2 2 1 1 a b c d e f g h White wins with 1.Rd8# Same back-rank mate position but with blocking knight a b c d e f g h 8 8 7 7 6 6 5 5 4 4 3 3 2 2 1 1 a b c d e f g h 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.

Luft

	a	b	c	d	e	f	g	h
8									8
7									7
6									6
5									5
4									4
3									3
2									2
1									1
	a	b	c	d	e	f	g	h

Black to move - Can black avoid back rank mate by moving his b pawn to make luft at b7 and attacking the white knight?

Queen sacrifice

	a	b	c	d	e	f	g	h
8									8
7									7
6									6
5									5
4									4
3									3
2									2
1									1
	a	b	c	d	e	f	g	h

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#

Check (chess)

	a	b	c	d	e	f	g	h
8									8
7									7
6									6
5									5
4									4
3									3
2									2
1									1
	a	b	c	d	e	f	g	h

White to move - 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

a b c d e f g h 8 8 7 7 6 6 5 5 4 4 3 3 2 2 1 1 a b c d e f g h White to move and mate in 3 moves.

a b c d e f g h 8 8 7 7 6 6 5 5 4 4 3 3 2 2 1 1 a b c d e f g h 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. 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.