C12(Chemical Analysis) Flashcards
What are pure substances
compounds or elements, that only contain one substance
What are impure substances
A mixture of two or more different elements or compounds
What are fixed points
The melting and boiling points of an element or a compound
Melting and boiling point data can be …
Used to distinguish pure substances from mixtures
What are formulations
Useful mixtures made up in definite proportions designed to give a product the best properties
Scientists can analyse unknown substances in solution by using …
Paper chromatography
What’s the formula to calculate the retention factor
What’s the positive test for hydrogen gas
A lighted splint pops
What’s the positive test for oxygen gas
A glowing splint relights
What’s the positive test for carbon dioxide
Limewater turns milky(cloudy white)
What’s the positive test for chlorine gas
Damp blue litmus paper turns white
What are flame tests
Some metals (cations) produce flames with a characteristic colour
What are the metal ions and their colours
How do you identify carbonates
-add dilute acid
-which produces carbon dioxide gas
-the gas turns limewater cloudy
How do you identify sulfates
-add hydrochloric acid then barium chloride solution
-this produces a white precipitate of barium sulfate
Method instrumental techniques provide …
Fast, accurate and sensitive ways of analysing chemical substances
What are the advantages of modern instrumental methods
-they are highly accurate and sensitive
-they are quicker
-they enable very small samples to be analysed
What are the disadvantages of modern instrumental methods
-it is very expensive
-takes special training to use
-gives results that can be interpreted by comparison with data from known substances
What does flame emission spectroscopy show us
-which metal ions are present from their characteristic line spectra
-the concentration of the metal ions in a solution
What is the effect of adding sodium hydroxide to metal cations
