Physical + Chemical Changes Flashcards
describe physical changes
physical changes are reversible and no new substances are formed.
e.g change in state
boiling water —> water
describe chemical changes
some chemical changes are reversible if the conditions are changed. the reaction can be reversed.
what is an example of a reversible chemical change?
(blue) hydrated copper (II) sulfate to (white) anhydrous copper (II) sulfate
CuSO^4^ (s) + 5H^2^O (l) <=> CuSO^4^.5H^2^O (s)
describe the process of anhydrous copper (II) sulfate and hydrated copper (II) sulfate
1) bunsen burner heats a bowl of hydrated copper (II) sulfate
2) water is driven off, leaving anhydrous copper (II) sulfate
3) the bunsen burner is turned off, and water is added using a pipette.
4) the bowl contains hydrated copper (II) sulfate again.
element
a substance which cannot be further divided into simpler substances by chemical methods. it is made up of only 1 type of atom.
mixture
a system of two or more substances that can be seperated by physical means
compounds
a substance formed by the combination of two or more elements in fixed proportions. the elements are chemically bonded together.
solvent
a liquid which dissolves a solute to form a solution
solute
soluble solid which dissolves in a solvent to form a solution
solution
this is formed when a substance (solute) dissolves into another substance (solvent)
concentration
a measure of the number of particles of the solute in the solvent
what is concentration measured in?
moles per dm^3
mol/dm^3
describe the reversible change between hydrated copper sulfate and anyhdrous copper sulfate
blue cooper sulfate is described as hydrated. the copper ions in its crystal lattice structure are surrounded by water molecules. the water is driven off when blue hydrated copper sulfate is heated, leaving white anhydrous copper sulfate. adding water reverses it back to hydrated copper sulfate
