Water

Water

Names
IUPAC name Water
Other names DHMO Dihydrogen monoxide Dihydrogen oxide Hydrogen oxide Oxidane Hydric acid Hydrogen hydroxide Hydrogenyl alcohol
Properties
Chemical formula	H2O
Molar mass	18.01528(33) g/mol
Appearance	Colorless liquid
Odor	Odorless
Density	See here
Melting point	0 °C (32 °F; 273 K) (ultrapure water can supercool as low as −48.3 °C)
Boiling point	100 °C (212 °F; 373 K)
Solubility	Reacts with acid anhydrides, acyl chlorides, certain inorganic chlorides, Miscible with some lower-chain liquids (alcohols, amines, carboxylic acids, cyclic ethers), acetaldehyde, acetone, acetonitrile, DMSO, DMF, hydrazine, hydrogen cyanide, nitric acid, sulfolane, sulfuric acid Slightly soluble in methyl ethyl ketone, methyl formate Immiscible with ethers, halocarbons, hydrocarbons
Vapor pressure	0.031276 atm (at 25 °C)
Acidity (pKa)	13.995
Thermochemistry
Std molar entropy (So298)	69.95 ± 0.03 J·mol-1·K-1
Std enthalpy of formation (ΔfHo298)	-285.83 ± 0.040 kJ/mol
Hazards
Safety data sheet	Sigma-Aldrich
Flash point	Non-flammable
Lethal dose or concentration (LD, LC):
LD50 (Median dose)	~100,000 mg/kg
Related compounds
Related compounds	Hydrogen peroxide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Water is a chemical compound with the formula H₂O and is a versatile solvent often used in the laboratory.

Properties

Chemical

Water the most commonly used laboratory solvent, due to its property of not being flammable like many other solvents, ability to dissolve a wide range of compounds, cheapness and availability, and non-toxicity as well as being mostly inert.

Self-ionization

Water is able to ionize and form hydronium and hydroxide ions in solution in concentrations of about one ten millionth of a molar.

Physical

Water is a colorless liquid with a density of 1.00g/ml, a boiling point of 100°C, and a freezing point of 0°C. It is odorless, tasteless, and somewhat volatile.

Availability

Distilled water is available at most grocery stores for less than one dollar per gallon. Tap water is essentially free. Some home setups for distillation of water can actually produce enough distilled water for lab use, but energy costs are a major concern.

Preparation

Water can be prepared by the ignition of any hydrocarbon or hydrogen. It can also be prepared by distillation of water from a lake or ocean, however none of the methods are economical due to the cheap price of water.

Projects

Water is a widely used solvent and is often the only solvent used in beginner inorganic chemistry, or it's more common term of "wet chemistry".

• Dissolving alkali metals in water
• Making hydroxides from metal oxides
• Hydrated crystals
• Ice crystals
• Cooling baths
• Oxoacids
• Generating hydrogen or oxygen via electrolysis
• Solvent extraction/washing

Handling

Safety

Ingestion of large amounts (really, really large amounts) of pure water can upset the osmotic balance is the body. The human body is composed mainly of water, though small amounts of any liquid, including water, can be fatal when inhaled, through a process commonly known as drowning.

It is recommended that a specific supply of distilled water is purchased.

Storage

Distilled water should be stored in closed bottles, away from heat or light sources to limit its evaporation, as well as to reduce its contamination with dust or other contaminants (otherwise you won't be needing pure water).

If you need ultrapure water for various sensitive analyses (such as pH), it's mandatory you air-tight the water bottle/containers, as water will rapidly absorb carbon dioxide from air, which lowers the pH.

Disposal

Down the drain the water goes. Or in the garden. Just be sure it's clean water.