Water: Difference between revisions
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==Uses== | ==Uses== | ||
===Primary=== | ===Primary=== | ||
* | * Water is essential to human life | ||
* In chemistry, it is a common polar solvent | * In chemistry, it is a common polar solvent | ||
* Ice is a key thermal absorption material | * Ice is a key thermal absorption material | ||
* Triple point is key in thermal measurement and calibration of thermometers. | * Triple point is key in thermal measurement and calibration of thermometers. | ||
===Secondary=== | ===Secondary=== | ||
* Expansion on freezing is a key mechanic in early stone splitting | * Expansion on freezing is a key mechanic in early stone splitting |
Revision as of 01:46, 21 June 2019
Template:Xxx Water, in the English language, is an inexact term. This article deals with the chemical compound H2O: pure water.
Uses
Primary
- Water is essential to human life
- In chemistry, it is a common polar solvent
- Ice is a key thermal absorption material
- Triple point is key in thermal measurement and calibration of thermometers.
Secondary
- Expansion on freezing is a key mechanic in early stone splitting
Natural occurrence
- Water occurs naturally
- as fresh water (ultimately derived from rain)
- Rain
- Springs
- Rivers
- Lakes
- and salt water from
- Oceans
- Seas
- Salt lakes
- Brine pools
- as fresh water (ultimately derived from rain)
- Structural water occurs in many minerals
- Many plants contain an abundance of water
Hazards
- Drowning
- Overconsumption (>= 2L/hr for multiple hours when normally hydrated) can lead to hyponatremia
Production
Extraction
Synthesis
from hydrogen gas
- Burn hydrogen in air, directing the combustion products to a condenser
- 2 H2 + O2{H2O(v)combustion}→
- 2 H2 + O2
- Condense the water formed
As a side product
Many chemical reactions, particularly acid/base reactions (e.g. acetic acid and calcium hydroxide), produce water as a side product.
- 2 CHCOOH + Ca(OH)2 → Ca(CH3COO)2 + 2 H2O // acetic acid and calcium hydroxide produce calcium acetate and water
Testing
Quantitative tests
- Density 1.0
- Melting point 0.1°C
- Boiling point 100°C
- pH 7.0
Qualitative tests
- Visual: Clear, colorless
- Smell: None
- Taste: Characteristic
- Approximate Viscocity : Characteristic
Purification
Filtration
- Passing water through clean, fine sand will remove some microorganisms.
- Passing water through charcoal or activated charcoal will remove toxins such as cyanide.
Arranging a filter with layers of sand and charcoal is an effective way to produce relatively clean water. It should still be boiled before drinking.
Distillation
- Distilled water is water that has been condensed from a gas. In simple cases this will render it both completely free of contaminants and totlly sterile.
- distil water
- discard residue
- distillate is distilled water
- NB: Some contaminants form fixed gaseous mixtures with water. (e.g. ammonia, ethanol, sulfuric acid) These are not easily removed by simple distillation.
Other
- The mineral witherite is sometimes used for the removal of calcium and magnesium sulfates from water via precipitation
- 2 BaCO3(s) + CaSO4(aq) + MgSO4(aq) → CaCO3(s) + MgCO3(s) + BaSO4(s)
Storage
Store in watertight containers.
Disposal
Water can be safely discarded into the environment