Chapter 3 Flashcards
coefficient
number of molecules
in front of the formulas
coefficients in a balanced chemical equation indicate the relative numbers of molecules (or formula units) in the reaction and the relative numbers of moles
combination reactions
two or more substances react to form one product
decomposition reaction
one substance undergoes a reaction to produce two or more other substances
combustion reaction
rapid reactions that produce a flame
involved O2 from air as a reactant
subscripts
number of atoms
formula weight
sum of atomic weights of atoms in the chemical formula of the substance
the formula weight equals the atomic weight
molecular weight
if the chemical formula is that of an molecule, the formula weight is also called the molecular weight
avogadro’s number
1 mol = 6.022X 10^23
empirical formula
tells the relative number of atoms of each element in the substance
the ratio of numbers of moles of all elements in a compound gives the subscripts in the compound’s empirical formula
to find this formula, you convert everything with moles and then divide the larger number of moles by the smaller number to obtain the mol ratio
molecular formula
subscripts in the molecular formula are always whole number multiples of the subscripts in the empirical formula
whole-number multiple = molecular weight/empirical formula weight
combustion analysis
a technique for determining empirical formulas
carbon is converted to CO2 and hydrogen to H2O
theoretical yield
quantity of product calculated to form when all of a limiting reactant is consumed
actual yield
amount of product actually obtained
always less than (and can never be greater than) the theoretical yield
percent yield
actual yield/theoretical yield X 100%
