- Smell: Most chemists can identify solvents by their distinctive smells (though this is a pretty bad idea). 1
- Melting point: If you’ve got very pure crystals, you can use their melting point to figure out which of several possible chemicals you’ve got.
What are other ways you could test what the unknown substance is?
- Gas Chromatography (GC)
- Gas Chromatography Mass Spectroscopy (GC-MS)
- Ion Chromatography (IC)
- High Performance Liquid Chromatography (HPLC)
- Dispersive Raman Spectroscopy.
- Fourier Transfer Infrared Spectroscopy (FTIR)
What tests can be done to identify an unknown substance?
Structures of unknown compounds can be determined by comparing physical properties, performing
functional group tests
, and checking melting points of derivatives against those of known compounds reported in the literature. Solubility properties and chemical reactivity become apparent during these qualitative tests.
What is the most accurate way to identify an unknown substance?
Raman Spectroscopy
Raman is a highly effective method for reliable identification of an unknown substance based on its underlying chemistry.
What properties can be used to identify an unknown substance?
All substances can be characterized by their unique sets of
physical and chemical properties
. Properties that can be determined without changing the composition of a substance are referred to as physical properties. Characteristics such as melting point, boiling point, density, solubility, color, odor, etc.
How do we identify substances?
- chemical name, for example, benzene;
- number, for example, EC number 200-753-7, and.
- chemical composition, for example, >99 % benzene and <1 % toluene. The composition is determined by chemical analysis.
How do you identify an unknown salt?
Students identify unknown chloride salts by (1) using
a precipitation reaction
to determine if the cation is a group 1 or group 2 metal, (2) performing a titration with silver nitrate to determine the formula mass of the salt, and (3) confirming the identity of the salt using a flame test.
What is an unknown sample?
Unknown/questioned sample –
evidence of unknown origin
; these samples could be found at a crime scene, transferred to an offender during commission of a crime, or recovered from more than one crime scene.
What can be used to identify a substance or to predict how it will behave?
Terms in this set (14) Why is it helpful to know the physical and chemical properties of a substance? Each substance has
a particular set of physical and chemical properties
. These properties can be used to identify a substance or to predict how it will behave.
What are three steps that can be used to identify a material?
- decide which properties to test.
- 2.do test on sample of the unknown.
- compare results with data reported for known materials.
Is density intensive or extensive?
Density is an
intensive property
of matter that illustrates how much mass a substance has in a given amount of volume.
What are 2 examples of properties?
Familiar examples of physical properties include
density, color, hardness, melting and boiling points, and electrical conductivity
. We can observe some physical properties, such as density and color, without changing the physical state of the matter observed.
Can you identify a substance by its density?
You can identify an unknown substance by measuring its density and comparing your result to a list of known densities.
Density = mass/volume
. … You can determine the volume by dropping the object into a graduated cylinder containing a known volume of water and measuring the new volume.
How can you say one substance is different from other?
Different substances have different properties;
density
is one property that can be used to tell two substances apart. Density is a property that does not depend on the shape or size of an object.
What is substance identity?
Substance identity is
established through the substance name
, related identifying numbers and information on the chemical structure, composition and purity of the substance which should be determined by chemical analysis.
Is table salt a pure substance?
Ordinary table salt is called sodium chloride. It is
considered a pure substance
because it has a uniform and definite composition. All samples of sodium chloride are chemically identical. Water is also a pure substance.
