physical and chemical change Flashcards
indicators of physical change
temperature of substance increases
change in size or shape
expected colour change
conductivity of metals decreases
substance may change phase
physical change
-identity of reactants and products remains unchanged
-overcoming forces
indicators of chemical change
unexpected colour change
gas formed
heat released/absorbed
precipitate (solid) formed
light produced
chemical change
atoms,molecules,ions rearrange themselves in new patterns and ratios
breaking bonds
synthesis reaction
chemical reaction where 2 or more simple substances are combined to form a complex product
A+B—>AB
decomposition reaction
one reactant produces 2 or more products
AB—>A + B
dissolution
soluble solid is placed into water and breaks down into smaller particles surrounded by water molecules
why does dissolution occur
because of the polar nature of water
dissociation
the splitting of an ionic compound into its ions
explain process of dissociation
formation of ions from ionic compounds
any ionic soluble substance
ionic salt further breaks down into anions and cations
ions separate away from each other by attraction of water molecules for them
what is formed when ionic substances dissociate in water
electrolyte
aqueous solution that can conduct electricity as the ions are free to move to carry charge
nitrates solubility
all soluble
group 1 compounds solubility
Li+, K+, Na+, NH4+
all soluble
Halides solubility
Cl-,Br-,I- most soluble
except Ag2+, Pb2+, Hg2+
Sulphates solubility
SO4 2-
Ba2+, Pb2+,Ca2+
Carbonates
CO3 2-
most insoluble
except Li+, K+, Na+, NH4+
silver chloride (s) colour
white