5. Formulae, Equations and Amounts Flashcards
(22 cards)
Mole
the amount of a substance that contains the same number of particles found in 12 g of 12 C.
Avogadro’s constant
The number of atoms in exactly 12 g of 12 C (6.02 x 10 23 mol − 1)
Molar mass
Mass of one mole of the substance expressed in gmol − 1
Empirical formula
Smallest whole number ratio of atoms of each element in a compound
Molecular formula
The actual number of atoms of each element in a molecule
Spectator ions
Ions that do not take part in the reaction
Mass concentration
mass of solute per volume of solution , gdm − 3
Molar concentration
moles of solute per volume of solution , moldm − 3
Molar volume
the volume of 1 mol of a gas
Displacement reaction
More reactive element reacts to take place of less reactive element in a compound
Precipitation reaction
produces an insoluble solid
Error
A discrepancy between the value obtained in the experiment and an actual value
Precision
Refers to how close to each other are the values obtained in an experiment
Accuracy
Refers to how close these values are to the actual value
Concordant results
Results that lie close to each other. In titration, these are titres that usually lie within +/ − 0.20 cm 3
Margin of error
The range in which the true value of a measurement could lie
Random errors
They occur when conditions are varied in an unpredictable manner
Systematic errors
Errors which are constant when you repeat an experiment. They usually are a result of the apparatus used
Percentage uncertainty
(Uncertainty/Reading) x 100%
Percentage yield
(Actual yield/Theoretical yield) x 100%
Atom economy
Measure of the proportion of reaction atoms that become part of the desired product in the balanced chemical equation
Atom economy equation
(Molar mass of desired product/Total molar mass of all products ) x 100%
