Chemical Analysis Flashcards
Definition of element
It’s a substance that consists of only one type of atom and it can’t be broken down into anything simpler by chemical means
Compound definition
It’s a substance that consists of two more different elements chemically bonded together
What is a pure substance?
It’s a single element or compounds
Mixture definition
It’s defined as two or more substances mixed together, which are usually easy to separate
What is a melting point?
The temperature at which a solid changes into a liquid
What is a boiling point?
The temperature at which a liquid changes into a gas
What happens in the presence of an impurity?
Lowers the melting point of a solid
Raises the boiling point of a liquid
What is filtration uses to separate?
An insoluble substance and a liquid e.g. sand and water
What is evaporation used to separate?
A solute from a solvent e.g. salt from salt water
What is simple distillation used to separate?
Solvent from a solution e.g. water from sea water
What is fractional distillation used to separate?
2 or more miscible liquids e.g. crude oil
What is chromatography used to separate?
2 or more substances in a solution e.g. food dyes or inks
How to calculate Rf?
Distance moved by sample divided by distance moved by solvent
What is potable water?
Water that is safe to drink
Water treatment?
Sedimentation & coagulation - filtration - chlorination - neutralisation
What is desalination?
The process of removing dissolved substance from sea water
Disadvantages of producing drinking water?
- It’s expensive because large amounts of energy are needed to heat the seawater
- It increases the use of fossil fuels-which are non-renewable
Test for chlorine
Damp universal indicator paper changes to red and then bleaches white
Test for cations (flame test)
Lithium - crimson
Sodium - yellow/orange
Potassium - lilac
Calcium - brick red
Copper - Blue -green
What is a precipitate?
A solid which may be formed on mixing two solutions
Test for cations (sodium hydroxide)
Copper - blue solution - blue ppt
Iron (II) - green solution - green ppt
Iron (III) - orange solution - brown ppt
Magnesium - colourless solution - white ppt
Aluminium - colourless solution - white ppt
Zinc - colourless solution - white ppt
Test for cations (ammonia solution)
Copper - blue solution - blue ppt
Iron (II) - green solution - green ppt
Iron (III) - orange solution - brown ppt
Magnesium - colourless solution - white ppt
Aluminium - Colourless solution - white ppt
Zinc - colourless solution - white ppt
Test for anions (halides)
Chlorine - white ppt
Bromine - cream ppt
Iodine - yellow ppt
Test for anions (sulfate ions)
White ppt will form
Test for anions (carbonate ions)
Limewater will turn from colourless to milky
