Purity Flashcards
What is an element?
Atoms with the same atomic number
What is a compound?
Two or more elements chemically joined together
What is a mixture?
Two or more different substances not chemically joined together
What is a pure material?
A material composed of only one type of particles with distinct properties
What is an alloy?
A mixture of at least two elements, one of which is a metal
How can you tell if a substance is pure?
Pure substances have an exact boiling point (impurities cause the boiling point to change)
What is the difference between the melting points of pure and impure substances?
Pure substances have higher melting points
Impure substances have lower melting points
What is the difference in boiling points of pure and impure substances?
Pure substances have lower boiling points
Impure substances have higher boiling points
What is a pure substance?
A substance consisting of only one element or compound
What is the difference in temperature of melting points of pure and impure substances?
Pure substances melt at a specific temperature
Impure substances melt over a range of temperatures
(Temperature stays the same when a pure substance changes state)
What does filtration separate?
An insoluble solid from a liquid
What is filtration useful for?
Separating excess solid reactant from a liquid
Why does filtration work?
Filter paper has tiny holes/pores in it which are large enough to let simple molecules and dissolved ions through, but not larger particles
What is crystallisation?
When a solvent is evaporated to leave behind a solute in crystal form
What is a solvent?
A substance that other substances are dissolved in (eg. Water in a salt solution)
