chemical quantities, reactions and equilibrium Flashcards
what is 1 mole
6.02 x 10*23 (which is avogadro’s number)
when was avogadro’s number (1 mole) developed
1811
in a calculation what do brackets suggest
that we have to multiply everything in the bracket by the number outside it
what is molar mass
this is the mass of a compound divided by the moles (g/mol)
how do we calculate molar mass
mass/ amount in moles (n)
how do we calculate mass
molar mass x amount in moles
how do we calculate moles
mass/ molar mass
what is concentration
the amount of a substance in a defined volume
what are the units of concentration
molarity (M)
how do you calculate concentration
molarity (M)= moles (mol)/ volume (L)
how do you calculates moles of a solution
molarity x volume
how do you calculate the volume of a solution
moles/ molarity
if you see a volume with ml as units what do you do
convert it into L by dividing it by 1000
what is the calculation for dilution
C1 x V1 = C2 x V2
what does C1 and V1 stand for
initial concentration and initial volume
what does C2 and V2 stand for
final concentration and final volume
what is the calculation for initial concentration
C2 x V2/ V1
what the calculation for initial volume
C2 x V2/ C1
what’s the calculation for final concentration
C1 X V1/ V2
what’s the calculation for final volume
C1 X V1/ C2
what are reversible reactions
a reaction that can go forward and back
what is an example of a reversible reaction
N2 + 3H2= 2NH3
2NH3= N2 + 3H2
what is equilibrium
when a forward reaction equal to the rate of the reverse reaction
what is the equation to represent equilibrium
rate F = rate R
(forward) (reverse)
describe what happens at equilibrium
the rate of the forward reaction is equal to the rate of the reverse reaction. the conc is changing but the reaction isn’t stopped
describe how equilibrium works for N2 + 3H2 = 2NH3
at the beginning of the reaction there is a lot of N2 and 3H2 and as the reaction continues the conc of N2 and 3H2 decreases. then the conc of 2NH3 increases. Finally, after dynamic equilibrium has been reached the concentrations don’t change anymore and the forward and reverse reactions are equal
what is the calculation for equilibrium constants
Kc= [D]d [E]e / [A]a [B]b
(the products are on top and reactants are on the bottom)
what does Kc show
shows the ratio of products and reactants at equilibrium
when adding molecules into the equilibrium constant equation where do you place the coefficient (number in front of molecule)
make it an exponent (as a power, number at the top)
what are the units of Kc
moles per litre
when was le chatelier principle developed
1884
what is le chatelier’s principle
if stress is applied to a system in dynamic equilibrium the system will be adjusted to relieve the stress
what happens when the pressure is increased but the volume is decreased
this favours the side with fewer moles so equilibrium is moved to the right
what happens when there is increased volume but decreased pressure
this favours the side with the most moles so equilibrium is moved to the left
describe what temperature does to the equilibrium constant
- when temperature changes so does Kc
- when the forward reaction is exothermic (releases heat = temp decreases) the reverse reaction is endothermic (takes in heat= temp increases)
