C12.1 - C12.6 - Chemical Analysis✔️ Flashcards
What is a pure substance?
A substance that is made up of just one substance - that substance can either be an element or compound
What are an elements fixed points?
The melting and boiling points of an element or a compound are called its fixed point
How can fixed points be used to identify pure elements and compounds?
Pure elements and compounds melt and boil at specific temperatures and these fixed points can be used to identify them - meltinga point and boiling point data can be used to distinquish pure substances
What are fomulations?
formulations are useful mixtures made up in definite proportions,designed to give a product the best properties possible to carry out its function
Why is chromatography used?
Used to seperate mixtures and give information to help identify substances - involves a stationary phase and a mobile phase - seperation depends on the distribution of susbstances between the phases
What are Rբ values?
Retention factor value which can be measured and matched against databases to identify substances
Equation for Rբ?
Rբ = distance moved by a substance / distance moved by solvent
What will happen to the compounds in a mixture when they seperate?
Compounds will seperate into different spots depending on the solvent - but pure compounds will produce a single spot in all solvents
What is the test for hydrogen?
Use 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?
Uses a glowing splint inserted into a test tube of the gas - splint relights in oxygen
What is the test for chemical dioxide?
Uses an aqueous solution or 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?
Uses litmus paper - which when damp blue litmus paper is put into chlorine the litmus paper is bleached and turns white
Colour for the lithium ion(Li+) in a flame test?
Crimson
Colour for sodium ion (Na+) in a flame test?
Yellow
Colour for potassium ion (K+) in a flame test?
Lilac
Colour for clacium ion (Ca2+) in a flame test?
Orange- red
Colour for copper ion (Cu2+) in a flame test?
Green
Explain how a flame test is set up?
- nichrom wire loop dipped in concentrated hydrochloric aicd and heated (to clean it)
- dipped in acid again before being dipped into metal compound being tested
- hold loap in roaring flame of bunsern burner
- use colour of flame to identify metal ion in the compound
Why is sodium hydroxide solution used?
Can be used to identify metal ions that form insoluble hydroxides in precipitation reactions
What ions form white precipitates when tested with sodium hydroxide solution?
- aluminium ions
- calcium ions
- magensium ions
What happens if you add more sodium hydroxide to aluminium ions,calcium ions and magensium ions?
The precipitate formed with aluminium ions dissolves however the white precipitate formed with calcium or magnesium ions will not dissolve (so calcium and magnesium can be distinguished by a flame test)
What colour precipitates forms with copper(II) ions?
Blue precipitate
What colour precipitates forms with iron(II) ions?
Green precipitate is produced
What colour precipitates forms with iron(III) ions?
Brown precipitate is formed
