Quantitative chemistry Flashcards
It is not always possible to obtain a calculated amount of products because:
- the reaction may not go to completion since it is reversible
- some of the product may be lost when it is separated from the reaction mixture
- some of the reactants may react in different way than expected
Relative formula mass of a molecule is also known…
as relative molecular mass.
Relative atomic mass
The average mass of the isotopes of the element weighted to take into account the abundance of each isotope. This is then compared with carbon-12 (6 protons and 6 neutrons).
A formula for relative atomic mass
Ar=( mass number of isotope 1 x percent abundance of isotope 1 )+(mass number of isotope 2 x percent abundance of isotope 2) / 100
The Mole
The relative atomic mass of any substance expressed in grams.
Relative formula mass of a compound…
is the sum of the relative atomic masses of the atoms in the numbers shown in the formula. Mr
Relative atomic mass is…
a mass number of elements. Ar
Abundance
How common it is.
One mole contains
6.02 x 10 (to the power of 23) atoms or molecules.
The mole number is known as…
Avogadro’s number.
Relative formula mass has…
- no units
- never involves big numbers
A formula for moles of an element
num of moles = mass (g) / relative atomic mass (Ar)
A formula for moles of a compound
num of moles = mass(g) / relative formula mass (Mr)
Empirical formula
The simplest ratio of each type of atom in the compound. It must be a whole number.
The concentration of a solution is related to…
the mass of the solute (moles) and the volume of the solution.
