Amount Of Substance Flashcards
(17 cards)
What is Ar?
The mean mass fo an element, divided by 1/12 of the mass of an atom of the C12 isotope
What is Mr?
The mean mass of a compound, divided by 1/12 of the mean mass of an atom of the C12 isotope
What is the Avogadro Constant (L)?
L = 6.022 X 10^23
How do we find the number of particles using the Avogadro constant?
Number of particles = nL (n=moles)
Moles equation 1
Mass = Moles x Mr
Moles equation 2
Moles = conc X vol/1000
When under standard conditions, what trends do gases and volatile liquids follow?
- pressure is proportional to temperature
- volume is proportional to temperature
- pressure and volume are inversely proportional
What is the ideal gas equation?
pV = nRT = mRT/Mr
What are the units?
p = pressure (Pascals)
V = volume (m^3)
T = temp (Kelvin)
n = moles
m = mass (grams)
R = ideal gas constant
What is the ideal gas constant?
8.31JK^-1mol^-1
What is empirical formula?
The simplest whole number ratio of atoms in each element of a compound
Calculating the true num of atoms in the molecule using empirical formula.
Mr/empirical Mr = multiplier
How do we calculate the empirical formula?
- divide each mass or percentage by Ar to find moles
- calculate the ratio by dividing all moles by the smallest number of moles.
What is percentage yield?
Shows how much product is obtained compared to maximum possible mass
Percentage yield equation
% yield =experimental mass / theoretical mass X 100
Atom economy equation
% atom economy = Mr of desired product / Mr of reactants X 100
Why is it good to have a high atom economy for a reaction?
- little to no waste product
- so more economically viable for industrial scale manufacture
- beneficial for environment as it uses less natural resources, so less energy
