Mole concept and stoichiometry Flashcards
Define relative atomic mass
The R.A.M. of an element is defined as the ratio of the average mass of one atom of the element to 1/12 of the mass of an atom of 12C isotope.
Define relative isotopic mass
The R.I.M. of a particular isotope is defined as the ratio of the mass of one atom of the isotope to 1/12 of the mass of an atom of 12C isotope.
Define relative molecular mass
The R.M.M of a substance is defined as the ratio of the average mass of one molecule of the substance to 1/12 of the mass of an atom of 12C isotope.
Define relative formula mass
The R.F.M. of an ionic compound is defined as the ratio of the average mass of one formula unit of the compound to 1/12 of the mass of an atom of 12C isotope.
Define mole in terms of the Avogadro constant
The mole is defined as the amount of substance containing exactly 6.02*10^23 / Avogadro’s constant elementary particles ( such as atoms, molecules, ions, formula units or electrons)
Formula for mole with Avogadro constant
No. of particles = n * L
Formula to calculate relative atomic mass from isotopic abundance
Ar = Sum of (relative isotopic mass * isotopic abundance)
What is Avogadro’s hypothesis?
Two equal volumes of gas, under the same temperature and pressure, contain the same number of molecules. (at constant temperature, mole ratio is equal to volume ratio for gases in balanced equations)
Define empirical formula
Empirical formula shows the simplest ratio of the atoms of the different elements in the compound.
What is the standard temperature, pressure and volume?
273K and 10^5 Pa/1 bar, 22.7dm^3
Define molecular formula
Molecular formula shows the actual number of atoms of each element in a compound.
What is the formula of combustion of hydrocarbons?
CxHy + (x+y/4) O2 –> xCO2 + (y/2) H20
Relationship of dilution
amount of solute (before) = amount of solute (after) / c1v1 = c2v2
Relationship of sampling
conc. of original solution = conc. of sampled solution / n1/v1 = n2/v2
