Amount of substance Flashcards
mole definition
the amount of substance in grams that has the same number of particles as there are atoms in 12 grams of carbon-12
relative atomic mass definition
the average mass of one atom compared to one twelfth of the mass of one atom of carbon-12
relative molecular mass
the average mass of a molecule compared to one twelfth of the mass of one atom of carbon-12
how to calculate moles equation
moles= mass/mr
calculation for gases
PV=nRT
calculation for conc
concentration= mole/volume
calculation for the no. particles
no. particles = mol of substance x Avogadro’s constant
density calculation
density= mass/volume
empirical formula definition
the simplest ratio of atoms of each element in the compound
molecular formula definition
the actual number of atoms of each element in the compound
making a solution process
-Weigh the sample bottle containing the required mass of solid on a 2 dp balance
-Transfer to beaker and reweigh sample bottle
-Record the difference in mass
-Add 100cm3 of distilled water to the beaker. Use a glass rod to stir to help dissolve the solid
-Pour solution into a 250cm3 graduated flask via a funnel
-Rinse beaker and funnel and add washings from the beaker and glass rod to the volumetric flask.
Remember to fill so the bottom of the meniscus sits on the line on the neck of the flask. With dark liquids like potassium manganate it can be difficult to see the meniscus.
Make up to the mark with distilled water using a dropping pipette for last few drops.
* Invert flask several times to ensure uniform solution.
percentage yield equation
actual yield/theoretical yield x100
percentage atom economy equation
percentage atom economy= mass of useful product/ mass of all reactants x 100
percentage uncertainty equation
% uncertainty= uncertainty/measurement made x 100
