Natriumhydroxid substansmängd

Physical properties

White orthorhombic crystals, produced in the form of pellets, lumps, sticks, beads, chips, flakes or solutions; hygroscopic; very corrosive; rapidly absorbs CO2 and water from the air; density 2.13 g/cm³; melts at 323°C; vaporizes at 1388°C; vapor pressure 1 torr at 739°C and 5 torr at 843°C; very soluble in water (110 g/100mL at room temperature), generating heat on dissolution; aqueous solutions highly alkaline, pH of 0.5% solution about 13 and 0.05% solution about 12; soluble in methanol, ethanol and glycerol (23.8 g/100 mL methanol and 13.9 g/100 mL ethanol at ambient temperatures.).

If too concentrated it may cause severe skin irritation.

Incompatibilities

A strong base and a strong oxidizer. (This and subsequent operations should be performed in a dry, CO2-free box.) The solution is concentrated under vacuum, using mild heating, to give a thick slurry of the mono-alcoholate which is transferred to a coarse sintered-glass disc and evacuated free of mother liquor.

INGESTION: severe damage to mucous membranes; severe scar formation or perforation may occur. Similarly, other metal ions are removed when a 1M (or more dilute) NaOH solution is passed through a column of Dowex ion-exchange A-1 resin in its Na+-form.

storage

splash goggles and impermeable gloves should be worn at all times when handling these substances to prevent eye and skin contact.

The bottle is then fitted with inlet and outlet tubes, the spent solution being flushed out by CO2-free N2. The amalgam is then washed thoroughly with a large volume of deionised water (with the electrolysis current switched on to minimize loss of Na). Finally, a clean steel rod is placed in contact in the solution with the amalgam (to facilitate hydrogen evolution), reaction being allowed to proceed until a suitable concentration is reached, before being transferred to a storage vessel and diluted as required [Marsh & Stokes Aust J Chem 17 740 1964].

Aqueous solutions are known as soda lye

Chemical Properties

Sodium hydroxide occurs as a white or nearly white fused mass. It is used to control pH and neutralize acids in chemical processes. Readily absorbs moisture from the air to give caustic semi-solids that attack aluminum and zinc with the evolution of flammable hydrogen gas.

In base metal flotation, the use of sodium hydroxide is rare. Sodium hydroxide is very deliquescent and on exposure to air it rapidly absorbs carbon dioxide and water. Se hjälpen.

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FARA