Compounds and Stoichiometry (4) Flashcards
Empirical formula
the smallest whole-number ratio of the elements in a compound.
(Empirical formula for benzene is CH, molecular is C6H6, ionic compounds will only have empirical formula).
Molecular formula
Either the same as or a multiple of the empirical formula; it gives the exact number of atoms of each element in a compound.
Percent composition
To calculate, determine the mass of the individual element and divide by the molar mass of the compound.
% composition = mass of element in formula / molar mass x 100
Combination rxn
occurs when two or more reactants combine to form one product.
2H2 + O2 –> 2H2O
Decomposition rxn
occurs when one reactant is chemically broken down into two or more products.
2HgO –> 2Hg + O2
Combustion rxn
occurs when a fuel and an oxidant ( typically oxygen) react, forming the products water and carbon dioxide.
CH4 + 2O2 –> CO2 + 2H2O
Single - Displacement Rxn
occurs when an atom or ion in a compound is replaced by an atom or ion of another element.
Cu + AgNO3 –> Ag + CuNO3
Double - Displacement Rxn
elements from two different compounds swap places with each other to form two new compounds.
CaCl2 + 2AgNO3 –> Ca(NO3)2 + 2AgCl
Neutralization rxn
acid reacts with base to produce salt and water
HCl + NaOH –> NaCl + H2O
Percent Yield
Actual / Theoritical x 100
Electrocytes
Ionic compounds make good electrolytes b/c they dissolve most readily. Nonpolar covalent compounds are the weakest b/c they do not form current-carrying ions.
HCl
MgBr2
-ous and -ic endings
- ous endings can also be used to indicate lesser charge
- ic endings indicate greater charge
(Fe2+ Ferrous)
(Fe3+ Ferric)
-ide
Monotomic anions ends with -ide
F- flouride
(O2- Oxide)
-ite and -ate endings
-ite the one with less oxygen
-ate the one with more oxygen
(NO2- = nitrite , SO3 2- = sulfite )
(NO3- = nitrate , SO4 2- = sulfate)
-Hypo and - per endings
ClO- = hypochlorite ClO2- = chlorite ClO3- = chlorate ClO4- = perchlorate
Gram equivalent weight (GEW)
Molar mass / n
n = quantitiy of interest (equivalent) (electron or H+ or OH-)
Equivalents
Mass of compound (g) / Gram equivalent weight (g) (GEW)
Normality (N)
the measure of concentration given in the units equivalents/liter
Molarity (mol/L) = Normality (equiv/L) / n
1 mol of any ideal gas at STP
22.4L
Limiting reagent
the reactant that will be consumed first in a chemical reaction.
All limiting reagent problems must be done in units of moles.
It is the rate at which the reactant is consumed, combined with absolute mole quantities determines which reactant is the limiting reactant.
Excess reagent
other reactant presents.
