reactions and stoichiometry Flashcards
definition of relative molecular mass (Mr)
the ratio of the average mass of one molecule of a substance to 1/12 the mass of one atom of C-12
definition of relative formula mass
the ratio of the average mass of one formula unit of a substance to 1/12 the mass of one atom of C-12
definition of the empirical formula
the empirical formula of a compound is the simplest formula which shows the ratio of the atoms of the different elements in the compound
definition of molecular formula
the molecular formula of a compound is the formula which shows the actual number of atoms of each element in one molecule of the compound
define Avogadro’s law
equal volumes of all gases, under the same temperature and pressure, contain the same number of particles
definition of acid and base in the Arrhenius Theory of Acids & Bases
An acid is a subtance that dissociates in water to produced H3O+
A base is a substance that dissociates in water to produce OH-
limited to aqueous solutions only
definition of acid and base in the Bronsted-Lowry Theory of Acids & Bases
An acid is defined as any species which donates a proton, H+
- must contain H in its formula
A base is defined as any species which accepts a proton, H+
- must contain a lone pair of electrons
definition of acid and base in the Lewis Theory of Acids & Bases
An acid is a species that accepts an electron pair
A base is a species that donates an electron pair
Lewis acid-base reaction is a transfer of a pair of electrons from the base to the acid.
definition of redox reaction
a reaction that involves reduction and oxidation simultaneously
what causes a substance to undergo reduction
gaining electrons, decrease in oxidation number, loses oxygen, gains hydrogen
what causes a substance to undergo oxidation
losing electrons, gain in oxidation number, gain in oxygen, lose hydrogen
definition of a reducing agent
a substance that gives electrons to another, itself being oxidised in the process
definition of an oxidising agent
a substance that takes in electrons from another, itself being reduced in the process
definition of disproportionation
a redox reaction in which the same substance is both oxidised and reduced.
oxidation numbers of O and H
H: +1 except in metal hydrides (NaH) which is -1
O: -2 except in peroxides (H2O2) which is -1
