Ph 2 Amount of substance Flashcards
moles of a solid equation
mass / Mr
moles of a solution equation
concentration x volume
ideal gas equation
pressure x volume = moles x gas constant x temperature
what is mass measured in for solid moles
grams
unit of concentration
mol dm-3
g dm-3
how to convert between units of concentration
multiply mol dm -3 by the Mr to get g dm-3
what is volume measured in for solutions equation
dm3
what are the units in the ideal gas equation
volume= m3 pressure = Pa temperature = Kelvins
1 ton in grams
1,000,000 grams
1 kg in grams
1,000 grams
1mg in grams
0.001 grams
limiting reagent
the reactant that limits the amount of moles of product that can be made, the other product is in excess meaning there will be some left over after the reaction.
m3 conversion =
cm3/1,000,000
dm3/1,000
pressure conversion
Pa = KPa x 1000 Pa= MPa x 1,000,000
temperature conversion
k=c + 273
what is an ideal gas?
a gas with no forces between molecules, all particles size is negligible
what can the ratio of the equation be used for
moles
volume of a gas
final volume
volume of products + volume of excess left over
what is atom economy?
a measure of the amount of starting materials that end up as useful products in theory
equation for atom economy
(total Mr of desired product / total Mr of reactants ) x 100
what is percentage yield?
Compares the mass of product you produce to the amount you expected. Practical based.
equation to calculate percentage yield
( actual yield / theoretical yield ) x 100
reasons why the actual yield may be lower than the theoretical yield
reversible reaction
reaction did not reach completion
other reactions occurred
product lost during isolation
what is relative molecular mass
the average mass of one molecule relative to 1/12 the mass of one atom of carbon twelve
what is the empirical formula
the simplest ratio of atoms of each element in a compound
what is the molecular formula
the actual ratio of atoms of each element in a compound
steps to find the empirical formula
1) write out the mass of percentage of that element in the compound
2) Divide by the Ar of the element
3) Divide by the smallest to get a to one ratio
4) Make ratio to whole numbers
how to find the molecular formula from the empirical formula
1) Find the Mr of the compound
2) divide the Mr of the compound by the Mr of the empirical formula
3) Multiply the empirical formula values by this amount.
how to find the mass of an element in a compound of known mass
mass of compound x (Ar of element/Mr of compound)
