Pure Substances And Mixtures Flashcards
What is a pure substance?
A substance which has had nothing added to it and has a fixed melting point
What is a…
Element?
Compound?
Mixture?
Element - a substance which only contains one kind of atom
Compound - substance w one or more atoms chemically joined
Mixture - two or more elements/compounds not chemically joined
Which separating technique can separate a mixture of liquids?
Simple distillation
Which separating technique can separate components of coloured compounds?
Chromatography
Equation for Rf value
Rf=distance travelled by component/distance travelled by solvent
Solid, liquid or gas?
a) highest density?
b) no fixed shape
c) can’t diffuse
d) can be compressed
e) takes up shape of container
a) solid
b) gas
c) solid
d) gas
e) liquid
How is the relative formula mass of a molecule calculated?
Adding relative atomic masses of all atoms
What are the properties of group 1 metals?
Soft and v reactive
React with water (strong alkaline solution)
Form +1 ions
Form colourless soluble salts
Increase in reactivity DOWN group
Low melting/boiling points (relative to other metals)
What are the properties of group 7 elements?
Highly reactive non metals HALOGENS diatomic coloured gas LESS reactive down group More reactive halogens displace less reactive halogens Low melting/boiling points
What are the properties of group 0 metals?
Noble gases
Inert
Monatomic
Low melting/boiling points
What is the test to identify oxygen?
A glowing splint will relight in the presence of oxygen
What precipitates do the halides form with silver nitrate?
Chlorides -> white
Bromides -> cream
Iodises -> pale yellow
What are the flame test colours for group 1 ions?
Lithium - red Sodium - yellow/orange Potassium - lilac Calcium - brick red Barium - apple green Copper (2) - green
What are the properties of transition metals?
Lustrous Hard and strong High density Malleable Ductile Good conductors High melting/boiling points
