Chemical Compounds
The molar mass of a compound is the sum of the atomic masses
ex: the molar mass of CO2 is 41.009g/mol
To find the number of moles given the grams of a certain compound, multiply the grams by 1 mol divided by the molar mass of the compound
ex: 20g of NaCl x (1 mol/(58.443g of NaCl)) = .34 mol
To find the number of atoms in a compound, find the mole and multiply it by 1 mole divided by 6.022x10^23
ex: 12.2182 grams of AgCl x (1 mol/ (143.32g)) = .08525mol x (6.022x10^23 atoms/(1mol)) = 5.134 x 10^22 atoms
To find the percent composition, take the molar mass of one element and divide it by the molar mass to the compound and do that for each element and multiply it by 100.
ex: Mg = ((24.305/95.211) x 100)= 25.528%
Cl2 = ((70.906/95.2110 x 100) = 74.472%
The Empirical Formula is the simplified version of the Molecular Formula
ex: the Empirical Formula is P2O5 and the Molecular Formula is (P2O5)n
the molar mass of the molecular formula for P2O5 is 283.988g
n= molar mass of MF/ molar mass of EF
n= 283.988g/141.943g = 2.00072 = 2
(P2O5)2 = P4O10
ex: the molar mass of CO2 is 41.009g/mol
To find the number of moles given the grams of a certain compound, multiply the grams by 1 mol divided by the molar mass of the compound
ex: 20g of NaCl x (1 mol/(58.443g of NaCl)) = .34 mol
To find the number of atoms in a compound, find the mole and multiply it by 1 mole divided by 6.022x10^23
ex: 12.2182 grams of AgCl x (1 mol/ (143.32g)) = .08525mol x (6.022x10^23 atoms/(1mol)) = 5.134 x 10^22 atoms
To find the percent composition, take the molar mass of one element and divide it by the molar mass to the compound and do that for each element and multiply it by 100.
ex: Mg = ((24.305/95.211) x 100)= 25.528%
Cl2 = ((70.906/95.2110 x 100) = 74.472%
The Empirical Formula is the simplified version of the Molecular Formula
ex: the Empirical Formula is P2O5 and the Molecular Formula is (P2O5)n
the molar mass of the molecular formula for P2O5 is 283.988g
n= molar mass of MF/ molar mass of EF
n= 283.988g/141.943g = 2.00072 = 2
(P2O5)2 = P4O10