Chapter 1 - Stoichiometry Flashcards
What is a mole?
Amount of a substance that contains 6.02 x 10^23 particles
What is Avogadro’s number?
6.02 x 10^23
What is the relative molecular mass?
(Mr)
Mass of a molecule compared to C-12
What is the molar mass?
(M)
Mass of 1 mole of any substance in g/mol
How do you get mass from moles?
m=nM
How do you get number of particles from moles?
N=nL
What is the molecular formula?
The number and types of atoms in a molecule
What is the empirical formula?
The lowest ratio of number and type of atoms in a compound
What is %composition by mass?
The abundance of a substance in a compound by mass
How do you find %composition?
1) Formula
2) Experiment
What is a word equation?
ie.
solid copper + an aqueous solution of silver (I) nitrate -> solid silver + aqueous copper (II) nitrate
What is a balanced chemical equation?
ie.
Cu(s) + 2AgNO3(aq) -> 2Ag(s) + Cu(NO3)2(aq)
What are subscripts in chemical equations?
(s) - solid
(l) - melted
(g) - gas
(aq) - dissolved in water
(al) - dissolved in alcohol
What is a stoichiometric coefficient?
The coefficient added before a molecule to balance the equation
What is an ionic equation?
All aqueous ionic materials break into ions
ie.
Cu(s) + 2Ag(aq) + 2NO3(aq) -> 2Ag(s) + Cu(s) + 2NO3(aq)
What is a net ionic equation?
Spectator ions are removed
ie.
Cu(s) + 2Ag(aq) -> 2Ag(s) + Cu(aq)
What is a single displacement reaction?
Non-metal: AB + C -> AC + B
Metal: AB + C -> CB + A
What is a double displacement reaction?
AB + CD -> CB + AD
What is a synthesis reaction?
A + B -> AB
What is a decomposition reaction?
AB -> A + B
Catalyst goes under arrow
What is a combustion reaction?
Combustion of a fuel produces oxides of elements in the fuel
ie.
CH4 + 2O2 -> CO2 + 2H2O
What is theoretical yield?
The max amount predicted by gravimetric stoichiometry
What is experimental yield?
The actual amount obtained experimentaly
How do you calculate %yield?
%yield = exp/theory x 100%
Why do theoretical and experimental yields differ?
1) Poor separation of product
2) Unwanted site reactions
3) Incomplete reaction
4) Transfer and preparation methods
5) (Purity of starting reagents)
How do you solve a gravimetric stoichiometry equation?
1) Balance the equation
2) Convert amount to moles: n=m/M or n=M/L
3) Use the equation
4) Convert moles to amounts: m=nM or N=nL
What is a limiting reagent?
The reactant that determines the amount of a product (often all used up in the reaction)
What is the excess reagent?
The reactant that is left over
