The mole, avogadro and the ideal gas equation

empirical formula

the simplest whole number ratio of an atom of an element in a molecule / compound

titration concordant results

within 0.10 cm3 or 0.05cm3

percentage uncertainty

max. uncertainty / measurement made on the equipment

number of atoms

MOLES x Avogadros constant (L)

name for .xH2O

water crystallisation

students readings

initial

end

titre (difference)

why it is important to fill the space below the tap in the burette with acid before beginning the titration

an incorrect volume would be recorded / gives a larger titre value

what the student should do next to obtain reliable results for the titration

repeat the titration to obtain concordant / consistent results

then calculate a mean titre

four additional instructions which would improve the students overall method

use a weighing boat to measure solid into

rinsing the solid from the weighing boat using distilled water to ensure no solid residue is left behind

transfer from beaker → volumetric flask using a funnel

ensure bottom of meniscus sits exactly on graduation mark of volumetric flask

Why sodium hydroxide solution rather than water should be used for the final rinse of the burette

use of water would dilute the concentration of NaOH

101 kPa

1 atmosphere (atm)

water crystallisation

water found in the crystalline framework of an ionic compound

remove all water (crystallisation)

heat + reweigh, repeat until constant mass (2x), heated until all water was driven away

molecular formula

the actual number of atoms of each element in a compound

Limiting factor

chemicals that get used up

It is the amount of this chemical that influences how much product you make

Excess

more than enough of this chemical , some will be left over

theoretical yield/ maximum yield

largest amount of product that could be made

actual yield

amount of product you made in an experiment (less than theoretical)

Atom economy

percentage value that indicates what percentage of our reactants turn into useful products

100% .. low % atom economy

expensive and wasteful

high % atom economy

less waste / fewer by products

sell by products → £££

minimises environmental impact = saves raw material, minimises waste, sustainability