Chapter 2 - amount of substance Flashcards
What is Mr?
The sum of the Ar’s of individual atoms in the compound found on the periodic table
Define the term relative molecular mass
The average mass of that molecule compare to 1/12 the mass of a carbon 12 atom
Define the term Avogadro’s constant
The number of atoms in 12g of carbon-12
What is Avogadro’s number?
6.02*10^23
Define the term mole
The amount of a substance that contains Avogadro’s number of particles
Define the term empirical formula
The simplest whole number ratio in which the atoms in a compound combine together
What is the ideal gas equation?
PV=nRT
What are the units for PV=nRT?
P - Pa, V - m^3, n - mol, R - J/mol/K, T - K
What does PV=nRT stand for?
P - pressure, V - volume, n - number of moles, R - gas constant (8.31), T - temperature
How do you convert celcius to kelvin?
Add 273
How do you convert kelvin to celcius?
take away 273
How do you convert cm^3 to m^3?
divide by 1000000
How do you convert dm^3 to m^3?
divide by 1000
How do you convert cm^3 to dm^3?
divide by 1000
What is the formula relating mass, Mr and moles?
mass=Mr*mole
What are the stages in calculating empirical formula? (and then molecular?)
Find the masses/percentages, divide each mass by corresponding Ar, divide by the smallest, round (and double/triple for molecular formula)
How do you get molecular formula from empirical formula when both Mr’s are given/ calculated?
Divide molecular Mr by empirical Mr and times each number of atoms by it
Define the term molecular formula
A formula that tells us the numbers of atoms of each different element that makes up a molecule of a compound
What is the last thing you do with any equation?
Include units and double check
What is the formula relating concentration, moles and volume?
mol=conc*vol
What are the units for mol=conc*vol?
mol, mol/dm^3, dm^3
What do you need to set up when doing a neutralisation calculation?
A table with mol, conc and vol down the left side and reactants at the top
What is the formula for percentage yield?
(actual/theoretical)*100
What is the formula for atom economy?
(useful/total)*100
