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EC number: 231-104-6 | CAS number: 7439-95-4
- Life Cycle description
- Uses advised against
- Endpoint summary
- Appearance / physical state / colour
- Melting point / freezing point
- Boiling point
- Density
- Particle size distribution (Granulometry)
- Vapour pressure
- Partition coefficient
- Water solubility
- Solubility in organic solvents / fat solubility
- Surface tension
- Flash point
- Auto flammability
- Flammability
- Explosiveness
- Oxidising properties
- Oxidation reduction potential
- Stability in organic solvents and identity of relevant degradation products
- Storage stability and reactivity towards container material
- Stability: thermal, sunlight, metals
- pH
- Dissociation constant
- Viscosity
- Additional physico-chemical information
- Additional physico-chemical properties of nanomaterials
- Nanomaterial agglomeration / aggregation
- Nanomaterial crystalline phase
- Nanomaterial crystallite and grain size
- Nanomaterial aspect ratio / shape
- Nanomaterial specific surface area
- Nanomaterial Zeta potential
- Nanomaterial surface chemistry
- Nanomaterial dustiness
- Nanomaterial porosity
- Nanomaterial pour density
- Nanomaterial photocatalytic activity
- Nanomaterial radical formation potential
- Nanomaterial catalytic activity
- Endpoint summary
- Stability
- Biodegradation
- Bioaccumulation
- Transport and distribution
- Environmental data
- Additional information on environmental fate and behaviour
- Ecotoxicological Summary
- Aquatic toxicity
- Endpoint summary
- Short-term toxicity to fish
- Long-term toxicity to fish
- Short-term toxicity to aquatic invertebrates
- Long-term toxicity to aquatic invertebrates
- Toxicity to aquatic algae and cyanobacteria
- Toxicity to aquatic plants other than algae
- Toxicity to microorganisms
- Endocrine disrupter testing in aquatic vertebrates – in vivo
- Toxicity to other aquatic organisms
- Sediment toxicity
- Terrestrial toxicity
- Biological effects monitoring
- Biotransformation and kinetics
- Additional ecotoxological information
- Toxicological Summary
- Toxicokinetics, metabolism and distribution
- Acute Toxicity
- Irritation / corrosion
- Sensitisation
- Repeated dose toxicity
- Genetic toxicity
- Carcinogenicity
- Toxicity to reproduction
- Specific investigations
- Exposure related observations in humans
- Toxic effects on livestock and pets
- Additional toxicological data
Additional physico-chemical information
Administrative data
Link to relevant study record(s)
Description of key information
Expert Judgement
Due to the absence of chemical groups or other structural alerts this substance is not considered to exhibit an high hazard potential.
Magnesium in Magnesium Alloys is from The alkaline earth metals: Its functional groups indicate low priority for further work based on a low hazard potential.
Therefore testing for Additional physico-chemical properties does not need to be performed.
Additional information
Expert Judgement
Due to the absence of chemical groups or other structural alerts this substance is not considered to exhibit an high hazard potential.
Magnesium in Magnesium Alloys is from The alkaline earth metals: Its functional groups indicatelow priority for further work based on a low hazard potential.
Therefore testing for Additional physico-chemical properties does not need to be performed.
Some Additional physico-chemical information is available:
Atomic properties
The unalloyed magnesium has the
following atomic characteristics:
1. Symbol: Mg.
2. Atomic number: 12.
3. Electron configuration in free
atoms: (2) (8) 2.
4. Orbital electron states in free
atoms: 1s2, 2s2, 2p6, 3s2.
5. Atomic isotopes 78.99% Mg24 (mass
= 23.98504), 10.00% Mg25 (mass
= 24.98584) and 11.07% Mg26 (mass
= 25.98259).
6. Atomic weight: 24.3050(6).
7. Atomic volume: 14.0 cm3/moll.
Crystal Structure
The crystal structure of pure
magnesium under atmospheric pressure is hexagonal close-packed. The
lattice parameters of pure magnesium at 25 oC
(77 oF)
were in agreement within ±0.01% of the assessed values of a (side
length) = 0.32092 nm and c (height)
= 0.52105 nm. The actual c/a ratio
at room temperature is 1.6236 making magnesium nearly perfectly closed
packed
. Mass
Characteristics
The
density of magnesium at 20 oC
(68 oF)
is 1.738 g/cm3 (0.0628
lb/in.3).
At the melting temperature (650 oC,
or 1202 oF),
the density in solid state is approximately 1.65 g/cm3 (0.0596
lb/in.3);
in liquid state, it is approximately 1.58 g/cm3 (0.0571
lb/in.3).
Volume
change on freezing. Volumetric
shrinkage of 4.2% occurs on freezing (1.5% linear shrinkage).
Volume
change on cooling. Volumetric
shrinkage of 5% occurs on cooling solid form from 650 oC
to 20 oC
(1202 oF
to 68 oF)
(1.7% linear shrinkage).
Thermal
properties
The
melting point of
pure magnesium under atmospheric pressure is 650 oC
± 1 oC
(1202 oF
± 1.8 oF).
The
boiling point of
pure magnesium under atmospheric pressure is 1090 oC
(1994 oF).
Thermal
expansion. The
coefficients of linear thermal expansion for polycrystalline magnesium
at low temperatures can be expressed as:
αt =
(25.0 + 0.0188t oC)
μm/m x oC
or
αt =
(13.7 + 0.0058t oF)
μ in/in. x oF
Thermodynamic
properties
Specific
heat capacities at constant pressure (Cp)
in units of J/mol x K are:
1.
Solid (298-923 K): 26.19 - 1.01 x 10-3 T
- 1.60 x 105/T2 +
8.41 x 10-6 T2
2.
Liquid (923-1600 K): 212.74 - 205.66 x 10-3T
- 350.15 x 105/T2 +
61.56 x 106
3.
Monatomic gas (298-2000 K): 20.79
4.
Monatomic gas (2000-3000 K): 22.12 - 1.24 x 10-3T
5.
Diatomic gas (298-900 K): 20.45 + 0.48 x 10-3T
+ 3.23 x 105/T2 -
0.19 x 106T
6.
Diatomic gas (900-3000 K): 20.78 + 2.71 x 105/T2
Electrical
properties
Electrical
conductivity is 38.6% IACS.
Electrical
resistivity (ρ) for single crystals of magnesium at 20 oC
(68 oF)
is 45.3 nΩ · m along the a-axis
and 37.8 nΩ · m along the c-axis.
The temperature coefficient at 20 oC
(68 oF)
is 0.143 nΩ · m/K along the c-axis.
The
contact potential is +44mV versus saturated calomel electrode at 25 oC
(77 oF)
and -0.222 mV versus copper at 27 oC
(81 oF).
The
electrochemical equivalent is 126 mg/C.
The
standard electrode potential is -2.40 V versus hydrogen.
The
ionization potential is 7.65 eV for Mg+ and
15.05 eV for Mg2+.
The
electrolytic solution potential is 1.63 mV versus saturated calomel
electrode at 25 oC
(77 oF)
in aerated NaCl solution.
The
Work Function. Two values have been published: 3.61 eV and 3.66 eV.
Magnetic
properties
Magnetic
susceptibility is 0.00627 to 0.00632 mks (mass)
Magnetic
permeability is 1.000012.
The
Hall constant is -1.06 x 10 -16 Ω
· m/(A/m)
Optical
properties
Reflectivity
is 0.72 at λ = 0.500 μm, 0.74 at λ = 1.00 μm, 0.80 at λ = 3.0 μm, 0.93
at λ = 9.0 μm.
Solar
absorptivity is 0.31.
Emissivity
is 0.07 at 22 oC
(72 oF).
The
absorption constant is 4.42 at λ = 0.589 μm.
The
refractive index is 0.37 at λ = 0.589 μm.
Nuclear
properties
Neutron
absorption cross-section values in barns per atom (1 barn = 10-24 cm2)
for thermal neutron radiation are:
0.063
± 0.004 for natural magnesium
0.03
± for Mg24
0.27
± for Mg25
0.03
± for Mg26
Magnesium
has the following radioactive isotopes: Mg21,
Mg22,
Mg23,
Mg27,
and Mg28.
The
x-ray absorption coefficient μm is 32.9 m2/kg.
Chemical Properties
(i) Action of oxygen or air
Magnesium does not react with dry air but slowly gets tarnished in most air due to the formation of a thin film of the oxide, MgO. It burns in oxygen or air with a dazzling light.
Δ
2Mg + O2 ——→ 2MgO
(ii) Action of CO2 and SO2
Because of its great affinity for oxygen magnesium keeps on burning even in CO2 or SO2.
Δ
2Mg + CO2 ——→ 2MgO + C
Δ
2Mg + SO2 ——→ 2MgO + S
(iii) Action of nitrogen
On heating magnesium combines with nitrogen to form magnesium nitride.
3Mg + N2 ——→ Mg3N2
Thus when magnesium burns in air both the oxide and the nitride are formed.
(iv) Action of halogens
Magnesium on heating with halogens readily forms the halides e.g.
Δ
Mg + CI2 ——→ MgCI2
(v) Action of water
Magnesium does not decompose water in cold but decomposes boiling water or steam.
Mg + H2O ( steam) ——→ MgO + H2
(vi) Action of Acids
Dilute acids reacts with magnesium to produce dihydrogen.
Mg + 2HCI ——→ MgCi2 + H2
Mg + H2SO4 ——→ MgSO4 + H2
(dil)
Mg + 2HNO3 ——→ Mg ( NO3)2 + H2
However with conc. H2SO4, SO2 is produced
Mg + 2H2SO4 ——→ MgSo4 + SO2 + 2H2O
(conc.)
(vii) Reaction with alkyl halide
Magnesium reacts with alkyl halides in dry ether to form covalent compound called Grignard reagent.
Dry ether
Mg + C2H5I ——→C2H5MgI
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