Chemical Analysis in FS Flashcards
Chemical Analysis
Analytic chemistry uses experiments and instruments to determine the physical properties or chemical composition of a substance.
Analysis may involve separation, identification and/or quantification.
States of Matter
Gas - atoms and molecules are widely separated and are able to freely move in relation to each other.
Liquid - atoms and molecules are loosely packed and able to move, but some order may exist.
Solid - atoms and molecules are tightly packed in a fixed regular manner.
Heterogeneous Mixtures
These are not uniform throughout, and contain two or more substances mixed together.
The substances are likely not evenly distributed and the mixture often contains visible differences.
Representative samples may be difficult to obtain.
Homogeneous Mixtures
These are uniform throughout, and contain two or more substances mixed together.
It must have the same uniform appearance and composition throughout.
Pure Substances
If matter is uniform and only composed of one substance, it is a pure substance.
If it can be separated into simpler substances it is a compound. If it cannot be separated, it is an element.
Knowing Types of Matter
Knowing the type of substance you are dealing with influences the dynamic risk assessments, and analysis options available.
For mixtures, the components may need to be separated, and for pure compounds analysis may be needed to figure out what it is exactly.
Identification
E.g identifying a suspect powder as containing a drug
Concentration
E.g. determining the concentration of a drug in a suspect powder
Cause and/or Effect
E.g. the drug ingested caused the death of the victim
Investigation of Cause/Effect
Formulate a hypothesis
Make a prediction from the hypothesis
Assess potential variables
Collect data
Assimilate data
Interpret the data
Accept or reject the hypothesis
Hypotheses - Inductive Reasoning
Sometimes a hypothesis may be considered to be supported by the prediction, but it does not ensure its truth.
