Moles Flashcards
Definition of Relative atomic mass (Ar)
average mass of the naturally occurring isotopes of the element relative to the mass of 1/12 of an atom of carbon-12
Definition of relative molecular mass (Mr)
mass of a molecule of the compound relative to 1/12 of an atom of carbon-12
Why are relative atomic masses “on average”?
weighted average of the naturally occurring isotopes of the element.
Definition of relative formula mass
When compound contains ions, it is the mass of the formula unit relative to the mass of 1/12 of an atom of carbon-12
How to find the number of molecules in a molecule?
mol x avagadro’s number
How to find mol of specific atoms in a molecule?
mol x how many of that atom
how to find number of specific atoms in a molecule?
number of molecules x however many of that atom.
mol of atoms x avagadro’s number
How to find percentage composition of a compound?
Find Mr
Divide amount of specific atom by the Mr.
x by 100.
Definition of empirical formula
the simplest whole number ratio of the elements present in a compound
definition of molecular formula
the actual number of atoms of each element present in a molecule of the compound
How to balance equations?
metals
non-metals
carbon
hydrogen
oxygen
What is the relationship between atom economy and the amount of waste?
Inverse relationship – lower atom economy, more waste.
What are the assumptions of an ideal gas?
consists of particles in constant, random motion.
Particles have no volume.
No force exists between particles (except when they collide)
All collisions between particles and between particles and the wall of the container are perfectly elastic (no change in total kinetic energy of colliding particles)
When do gases deviate most from ideal behaviour?
at high pressure and low temperature
What is avagadro’s law?
equal volumes of ideal gases measured at the same temperature and pressure contain the same number of molecules
What is 0°C in Kelvin?
273.15K
What is 0K in °C?
-273.15°C
What is the relationship between pressure and volume? (Boyle’s law)
volume of a fixed mass of an ideal gas is inversely proportional to its pressure at constant temp.
Draw graph of PV
|
|
|
<_______________
(curve not touching sides)
Draw graph of P 1/V
(Diagonal from origin)
Draw graph of PV vs P
(horizontal from middle of PV)
What is the relationship between volume and temperature? (Charles’ Law)
volume of fixed mass of ideal gas directly proportional to temp in Kelvin.
Draw graph of V vs T (in °C and K)
(K diagonal at origin)
(°C diagonal from -273.15°C)
What is the relationship between Pressure and temperature (Gay-Lussac’s Law)
fixed mass of ideal gas at constant volume, pressure is directly proportional to its absolute temp
What are the units of PV=nRT
P: Nm^-2 or Pa
V: m^3
T: K
1m^3 = ____dm^3
1000dm^3
1m^3 = _____cm^3
1000000cm^3
