Chemical Analysis Flashcards
What is a pure substance?
In chemistry, a pure substance is a single element or compound, not mixed with any other substance.
What can melting and boiling points be used for in pure substances?
Pure elements and compounds melt and boil at specific temperatures. Melting point and boiling point data can be used to
distinguish pure substances from mixtures.
What is a formulation?
A formulation is a mixture that has been designed as a useful product. Many products are complex mixtures in which each
chemical has a particular purpose.
How are Formulations made?
. Formulations are made by
mixing the components in carefully measured quantities to ensure
that the product has the required properties. Formulations include fuels, cleaning agents, paints, medicines, alloys, fertilisers and foods.
What can chromatography be used to do?
Chromatography can be used to separate mixtures and can give information to help identify substances. Chromatography involves a stationary phase and a mobile phase. Separation depends on the distribution of substances between the phases.
What does mixtures separating in chromatography depend on
Different compounds have different Rf values in different solvents, which can be used to help identify the compounds. The compounds
in a mixture may separate into different spots depending on the solvent but a pure compound will produce a single spot in all
solvents.
What is the test for hydrogen?
The test for hydrogen uses a burning splint held at the open end of a test tube of the gas. Hydrogen burns rapidly with a pop sound.
What is the test for oxygen?
The test for oxygen uses a glowing splint inserted into a test tube of the gas. The splint relights in oxygen
What is the test for carbon dioxide?
The test for carbon dioxide uses an aqueous solution of calcium hydroxide (lime water). When carbon dioxide is shaken with or bubbled through limewater the limewater turns milky (cloudy).
What is the test for chlorine?
The test for chlorine uses litmus paper. When damp litmus paper is put into chlorine gas the litmus paper is bleached and turns white.
