|
Element Index
Cadmium
Calcium
Carbon
Cerium
Chlorine
Chromium
Cobalt
Copper
Hydrogen
Chemical's truth
|
Ricin is a natural poison extracted from the castor oil bean with a quoted LD50 of 20,000 ng/kg. |
|
A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
P
Q
R
S
T
U
V
W
X
Y
Z
|
|
Calcium hydroxide
(slaked lime, calcium hydrate)
CAS no: 1305-62-0 Formula: Ca(OH)2 Molecular weight: 74.093
Physical Data
Appearance: Fine, powdry hexagonal crystalline with bitter alkaline taste.
|
Melting point: 580°C (decompose)
Boiling point: -
|
Density: ~2.2 g/cm3
Solubility: 0.160 g/100 g H2O (20°C)
Solubility product: 5.02 x 10-6
|
|
|
Thermodynamic Data
Enthalpy of formation: -985.2 kJ/mol
Gibbs energy of formation: -897.5 kJ/mol
|
Entropy: 83.4 J/mol K
Heat capacity: 87.5 J/mol K
|
|
|
Production and preparation
Manufacture industrially by adding water to calcium oxide (quicklime).
This is a strongly exorthermic reaction. In the laboratory, it is sometimes prepared by addition of an alkali to an aqueous
solution of a calcium salt, such as calcium chloride.
|
|
|
Behavior and Chemical Properties
Calcium is slightly alkaline, with a pH of upto 12.4 for saturated solutions at the room temperature. When heated, it decomposes to become calcium oxide,
of which the hydroxide is also made from, by adding the water.
When carbon dioxide gas is bubbled into an aqueous solution of calcium hydroxide, it forms a white precipitate of the carbonate.
When more carbon dioxide is passed, the precipitate eventually redissolves to give a clear, colorless bicarbonate solution.
|
|
|
History and Uses
In agriculture, it is used to reduce soil acidity and as a cheap alikali source in many industrial processes. It is also used in mortar, plaster,
cement and other building materials such as coatings (white wash).
In medicine, it is used to treat acid burns and as an antacid.
In laboratory, calcium hydroxide solution is used to test for the presence of carbon dioxide, with a white, cloudy calcium carbonate precipitate. It is also
used as water softener and filler (by adding carbon dioxide to produce white calcium caronate) in paper production to enhance the paper's whiteness,
opacity and texture.
|
|
|
Hazard, Storage and Handling
Keep in an air-tight container and store in a cool, dry, well-ventilated area.
Harmful if swallowed or inhale. LD50 for rats = 7.34 g/kg. It causes burns to skin and eyes. The dust can cause severe irritation to respiratory tract.
If swallowed can cause severe pain, vomiting, diarrhea and difficulty in swallowing. Do not induce vomitting. If still concious, give large quantity of water and call a physician
immediately. If it is skin or eye contact, flush with plecty of water for at least 15 minutes. Call a physician immediately.
|
|
|
(Last update: December 2004) |
A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
P
Q
R
S
T
U
V
W
X
Y
Z
|
|
