2.1.3 Amount of substance Flashcards
Molecular formulae
number of atoms of each element in a molecule
Empirical formulae
simpliest whole number ratio of atoms of each element in a compound
Relative molecular mass
compares mass of molecule with mass of C12
dm3 to cm3
x1000
concentration definition
amount of solute in moles dissolved in each 1dm3 of solution
moles equations
mass/molar mass
volume/molar volume
volume x concentration
molar volume
24 dm3
24 000 cm3
Ideal gas equation
pV=nRT
what is R in the ideal gas equation
ideal gas constant
8.314 J mol-1 k-1
units for temperature in the ideal gas equation
kelvin
units for volume in ideal gas equation
m3
units for pressure in ideal gas equation
Pa
cm3 to m3
x10-6
dm3 to m3
x 10-3
degrees to kelvin
+273
KPa to Pa
x 1000
what do molecules in the Ideal gas law show
random motion
negligible size
no intermolecular forces
how does pressure arise
due to collisionsbetween gas molecules and the size of the container theyre in pressure builds up
what does pressure depend on
number of particles in a container
size of container
the absolute container
percentage uncertainity
(error x number of readings/quantity measured ) x100
error
half the resolution unless a digital reading then its just the resolution
Avogadros constant
6.02 x10^23
Acids
contain hydrogen
what do acids do when in water
release hydrogen as protons
H+
Strong acid
e.g HCl
releases H+ ion in solution and dissolves completely by completely dissociating
weak acid
e.g CH3COOH
only releases H+ ion and only partially dissociates
Alkali
a base that dissolves in water releasing OH- ions
Acid + alkali
salt + water
Acid + metal oxide or metal hydroxide
Salt + water
acid + carbonates
Salt + water + carbon dioxide
molecules in ideal gas law
show random motion
have negligible size
no intermolecular forces - bounce off each other when they collide
