1.2 - amount of substance Flashcards
what is the mole?
the amount of substance in grams that has the same
number of particles as there are atoms in 12 grams of carbon-12
what is relative atomic/molecular mass?
the average mass of one atom/molecule compared to one twelfth of the mass of one atom of carbon-12
Avogadro’s constant?
- 6.022 x 10^23
- One mole of any specified
entity contains 6.022 x 10^23 of that entity
mole calculation for gases?
pressure(Pa) x volume(m^3) = temperature(K) x moles x R(8.31)
mole calculation for pure solids, liquids and gases?
mass = Mr x moles
how to get from K to C* in temperature?
C* = K + 273
equation for number of particles?
moles x Avogadro’s constant
mole calculation in solution?
moles = concentration x volume
density equation?
density = mass/volume
what is empirical formulae?
the simplest ratio of atoms of each element in the compound
how to convert from cm3 to dm3?
divide by 1000
equation for mass concentration?
mass/volume
method for PAG 1a? - making a standard solution
- calculate mass of sodium hydrogensulfate solid needed to produce 250cm3 of 0.100 mol dm-3 solution (should be 3g)
- weigh out a clean dry weighing bottle or boat
- place weighing boat on pan of digital balance, and using a spatula, place into the boat approximately the mass of sodium hydrogensulfate you calculated
- weigh weighing boat and its contents accurately and record precise mass
- pour contents of weighing boat into beaker and reweigh boat
- calculate mass of sodium hydrogensulfate you have transferred
- add approximately 100cm3 of distilled water to beaker containing solid and use glass rod to stir contents until solid dissolves
- using a funnel pour contents into a volumetric 250cm3 conical flask then using wash bottle rinse the beaker and funnel into same conical flask
- make volumetric flask up to graduated mark using distilled water from wash bottle, make sure bottom of meniscus is at graduated mark
- stopper volumetric flask and shake until contents are fully mixed
- calculate exact concentration of your solution in mol dm-3
method for PAG 1b? - carry out simple acid-base titration
- pour approximately 100cm3 of sodium hydrogensulfate into clean, dry, labelled beaker
- pour approximately 100cm3 of sodium hydroxide into a different clean, dry, labelled beaker
- fill a burette with the sodium hydrogensulfate at eye level and secure in clamp stand
- using a volumetric pipette, add exactly 25.0cm3 of sodium hydroxide into a 250cm3 conical flask
- put conical flask on white tile
- add 2 to 3 drops of phenolphthalein indicator to conical flask with solution in
- before you start to titrate, construct a able for your results
- record initial burette reading accurately
- open burette tap and slowly add sodium hydrogensulfate into conical flask whilst swirling gently
- near endpoint add it dropwise and close burette tap when solution in conical flask turns from pink to colourless
- calculate and record volume of sodium hydrogensulfate needed to neutralise sodium hydroxide
- repeat until you obtain concordant results then calculate mean volume
- use results to calculate concentration of sodium hydroxide
how to calculate new diluted concentration?
original concentration x original volume/new diluted volume
