There are no facts in science – only measurement embedded within assumptions.
Posted by: Antony Williams in UncategorizedCopyright©2008 Antony Williams
Jean-Claude Bradley, our collaborator at Drexel University, recently posted on “There are no facts…in science – only measurement embedded within assumptions.” He refers to information on ChemSpider a number of times to make his arguments and I point you to his original post to read.
Some specific sections are quoted “There are properties that have been determined so many times by different researchers and different techniques that we can treat a narrow range of values by consensus as if they were absolute facts. An example would be considering the boiling point of methanol at 1 atm to be 65C within one degree of accuracy. For most purposes that will suffice, as long as we understand the source of our confidence.”
When we deposit property information onto ChemSpider we make attributions with the outlinks. So, if you look at this record for ethyl acetate you will see a lot of property informtion listed as shown below. Unfortunately the “units” are not always directly available when we gather the data and we need to add the ability to add/edit units soon. However, there IS generally information in the record for at least one of the entries defining the units and the outlinks (shown by the blue arrows) will take the user to the original data source anyway.
- experimental physchem properties
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Melting Point: -84
The melting point of a crystalline solid is the temperature range at which it changes state from solid to liquid. See also: Melting Point
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Melting Point: -84
The melting point of a crystalline solid is the temperature range at which it changes state from solid to liquid. See also: Melting Point
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Melting Point: -84
The melting point of a crystalline solid is the temperature range at which it changes state from solid to liquid. See also: Melting Point
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Melting Point: -84
The melting point of a crystalline solid is the temperature range at which it changes state from solid to liquid. See also: Melting Point
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Melting Point: -84
The melting point of a crystalline solid is the temperature range at which it changes state from solid to liquid. See also: Melting Point
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Melting Point: -84 C
The melting point of a crystalline solid is the temperature range at which it changes state from solid to liquid. See also: Melting Point
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Boiling Point: 76-77
The boiling point of a liquid is the temperature at which the vapor pressure of the liquid equals the environmental pressure surrounding the liquid. See also: Boiling Point
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Boiling Point: 77
The boiling point of a liquid is the temperature at which the vapor pressure of the liquid equals the environmental pressure surrounding the liquid. See also: Boiling Point
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Boiling Point: 77
The boiling point of a liquid is the temperature at which the vapor pressure of the liquid equals the environmental pressure surrounding the liquid. See also: Boiling Point
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Boiling Point: 77
The boiling point of a liquid is the temperature at which the vapor pressure of the liquid equals the environmental pressure surrounding the liquid. See also: Boiling Point
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Boiling Point: 77
The boiling point of a liquid is the temperature at which the vapor pressure of the liquid equals the environmental pressure surrounding the liquid. See also: Boiling Point
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Boiling Point: 171F
The boiling point of a liquid is the temperature at which the vapor pressure of the liquid equals the environmental pressure surrounding the liquid. See also: Boiling Point
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Boiling Point: 77º
The boiling point of a liquid is the temperature at which the vapor pressure of the liquid equals the environmental pressure surrounding the liquid. See also: Boiling Point
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Boiling Point: 77 C
The boiling point of a liquid is the temperature at which the vapor pressure of the liquid equals the environmental pressure surrounding the liquid. See also: Boiling Point
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Flash Point: -3(26F)
The flash point of a flammable liquid is the lowest temperature at which it can form an ignitable mixture in air. See also: Flash Point
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Flash Point: -3(26F)
The flash point of a flammable liquid is the lowest temperature at which it can form an ignitable mixture in air. See also: Flash Point
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Flash Point: -3(26F)
The flash point of a flammable liquid is the lowest temperature at which it can form an ignitable mixture in air. See also: Flash Point
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Flash Point: -3(26F)
The flash point of a flammable liquid is the lowest temperature at which it can form an ignitable mixture in air. See also: Flash Point
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Flash Point: -3(26F)
The flash point of a flammable liquid is the lowest temperature at which it can form an ignitable mixture in air. See also: Flash Point
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Flash Point: 24F
The flash point of a flammable liquid is the lowest temperature at which it can form an ignitable mixture in air. See also: Flash Point
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Flash Point: -4 C
The flash point of a flammable liquid is the lowest temperature at which it can form an ignitable mixture in air. See also: Flash Point
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Freezing Point: -117F
No description available
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Specific Gravity: 0.902
Specific gravity is defined as the ratio of the density of a given substance to the density of water, when both are at the same temperature. See also: Specific Gravity
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Specific Gravity: 0.902
Specific gravity is defined as the ratio of the density of a given substance to the density of water, when both are at the same temperature. See also: Specific Gravity
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Specific Gravity: 0.902
Specific gravity is defined as the ratio of the density of a given substance to the density of water, when both are at the same temperature. See also: Specific Gravity
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Specific Gravity: 0.902
Specific gravity is defined as the ratio of the density of a given substance to the density of water, when both are at the same temperature. See also: Specific Gravity
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Specific Gravity: 0.902
Specific gravity is defined as the ratio of the density of a given substance to the density of water, when both are at the same temperature. See also: Specific Gravity
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Specific Gravity: 0.90
Specific gravity is defined as the ratio of the density of a given substance to the density of water, when both are at the same temperature. See also: Specific Gravity
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Specific Gravity: 0.894 – 0.898
Specific gravity is defined as the ratio of the density of a given substance to the density of water, when both are at the same temperature. See also: Specific Gravity
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Refraction Index: 1.3720
The refractive index (or index of refraction) of a medium is a measure for how much the speed of light (or other waves such as sound waves) is reduced inside the medium. See also: Refraction Index
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Refraction Index: 1.3720
The refractive index (or index of refraction) of a medium is a measure for how much the speed of light (or other waves such as sound waves) is reduced inside the medium. See also: Refraction Index
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Refraction Index: 1.3720
The refractive index (or index of refraction) of a medium is a measure for how much the speed of light (or other waves such as sound waves) is reduced inside the medium. See also: Refraction Index
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Refraction Index: 1.3720
The refractive index (or index of refraction) of a medium is a measure for how much the speed of light (or other waves such as sound waves) is reduced inside the medium. See also: Refraction Index
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Refraction Index: 1.3720
The refractive index (or index of refraction) of a medium is a measure for how much the speed of light (or other waves such as sound waves) is reduced inside the medium. See also: Refraction Index
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Refraction Index: 1.371 – 1.376
The refractive index (or index of refraction) of a medium is a measure for how much the speed of light (or other waves such as sound waves) is reduced inside the medium. See also: Refraction Index
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Ionization Potential: 10.01 eV
No description available
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Vapor Pressure: 73 mmHg
No description available
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- miscellaneous
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Appearance: Colorless liquid with an ether-like, fruity odor.
Visual appearance of the given substance.
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Appearance: colourless liquid with fruit-like odour
Visual appearance of the given substance.
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Appearance: Colourless liquid, volatile at low temperatures with a fragrant, acetic, ethereal odour
Visual appearance of the given substance.
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Applications: Pesticide residue, environmental, and GC analysis
No description available
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Stability: Stable. Incompatible with various plastics, strong oxidizing agents. Highly flammable. Vapour/air mixtures explosive. May be moisture sensitive.
Chemical stability occurs when a substance is in a (dynamic) chemical equilibrium with its environment. See also: Chemical Stability
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Toxicity: ORL-RAT LD50 5620 mg kg-1, SKN-RBT LD50 > 20 ml kg-1, SCU-GPG LD50 3000 mg kg-1, IPR-MUS LD50 709 mg kg-1
Toxicity is the degree to which something is able to produce illness or damage to an exposed organism. See also: Toxicity and list of used abbreviations.
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Safety: FLAMMABLE / IRRITANT
See Chemical Safety
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Safety: DANGER: FLAMMABLE, irritates skin, eyes, lungs
See Chemical Safety
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Safety: DANGER: FLAMMABLE, causes CNS injury, lung & eye irritation
See Chemical Safety
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Safety: DANGER: FLAMMABLE, causes CNS injury, lung & eye irritation
See Chemical Safety
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Safety: DANGER: FLAMMABLE, causes CNS injury, lung & eye irritation
See Chemical Safety
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Safety: Safety glasses, adequate ventilation.
See Chemical Safety
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First Aid: Eye: Irrigate immediately Skin: Water flush promptly Breathing: Respiratory support Swallow: Medical attention immediately
No description available
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Exposure Routes: inhalation, ingestion, skin and/or eye contact
No description available
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Symptoms: Irritation eyes, skin, nose, throat; narcosis; dermatitis
No description available
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Target Organs: Eyes, skin, respiratory system
No description available
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Incompatibilities and Reactivities: Nitrates; strong oxidizers, alkalis & acids
No description available
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Personal protection and Sanitation: Skin: Prevent skin contact Eyes: Prevent eye contact Wash skin: When
contaminated Remove: When wet (flammable) Change: No recommendation
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Jean-Claude goes on to discuss his project regarding the measurement of non-aqueous solubility and the differences between experimental and predicted properties. His discussions highlight the advantages of Open Notebook Science in terms of access to information regarding how measurements are performed…information that is missing otherwise. We advocate access to this type of information and will be linking to JC’s non-aqueous solubility measuresment on his wiki shortly. FYI, his entire presentation is online here.
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October 29th, 2008 at 3:54 am
The way ChemSpider aggregates different properties with links to the sources was ideal for the point I wanted to make about the boiling point of methanol for example. I wish chemical properties on Wikipedia had links to sources consistently.