amount of substances Flashcards
what is the equation for mols
mols=mass/mr
what is Avogadro’s constant
6.022x1023 - number of atoms in 12g of c12
titration accuracy
-remove bubbles from burette tap otherwise the volume of the air bobble will be counted in the burette reading
-remove funnel used to fill the burette before staring the titration as solution drops could fall from the funnel into the burette and affect burette reading
-during the titration swirl the conical flask and rinse the walls of the conical flask with distilled water so ensures all reactants mix and no reagent is left unreacted on the sides of the flask - doesn’t change the number of moles
steps to make a standard solution
1- transfer known mass of solid
weigh sample bottle containing the solid on a 2.dp balance scale
transfer to beaker and reweigh sample bottle
record difference in mass
2-dissolve in water
add distilled water
stir with glass rod
until all solid is dissolved
3-transfer, washing and agitation
transfer to volumetric flask using funnel wish washings
make up to 250cm3 and shake
relative molecular mass definition
average mass of 1 molecule
relative atomic mass definition
relative atomic mass is the average mass of 1 atom of an element - 1/12th the mass of a c12 atom
ideal gas equation
pv=nrt
p-pressure in pa
v-volume in m3
n- number of mols
r- molar gas constant -8.31
t-temp in kelvin
how to reduce % error
increase the concentration of solution in conical flask
decrease conc of solution in burette
how to calculate percentage error
percentage error = error the equipment / amount measured x 100
how to calculate number of particles
number of particles = mols x avagadros constant
how to calculate conc
conc = mols/vol
how to calculate atom economy
atom economy = mass of desired products/ total mass of reactants x 100
how to calculate % yield
% yield = actual yield/theoretical yield x 100
important as increases the amount of product that is made from the reactants
% yield can be improved by making improvements in experiment tecniques
