Equilibria Flashcards
True or false. at chemical equilibrium the rate of forward reaction = the rate pf reverse
True
do concentration of reaction and products stay the same at chemical equilibrium?
Yes
what does {} mean in notes
concentration
what is a species in chemistry?
reactants + products
what is a closed system in chemistry?
when none of the species (reactants or products) can escape
what is an open system in chemistary?
energy can be lost to surroundings
is equilibrium achievable outside reversible reactions?
No, it is only achievable in reversible reactions
what are the base units for concentration?
mol dm^-3
at equilibrium, it will appear as if no reaction is occurring. why?
because both the forward and reverse reactions are happening at the same rate
what is position of equilibrium
it refers to the relative amounts of reactants and products at equilibrium
what does it mean when the reverse reaction is faded (equilibrium shifts to the left)
more reactant is formed and less product (i.e., rate of reverence increases and forward decreases)
what does it mean if the forward reaction is faded (equilibrium shifts to the right)
more product is formed and less reactant (i.e. rate of forward reaction increases and reverse decrees)
what is Le Chaterlier’s Principle?
if a change is made to a system at dynamic equilibrium, the position of equilibrium moves to minimize/oppose this change
what will happen when we increase the concentration of one side of a reaction
by Le Chaterliers principle it will oppose the shift (i.e shift to the opposite side of the increased concentration)
in equation A(g) + B(g) <-> 3C(g) which side represents the lower pressure and if the pressure is increased which direction will the equilibrium shift?
reactants are 2 mols, product is 3 mols the products therefore represent the higher pressure.
if the pressure is increased by Le Chateliers principle equilibrium will shift to the left
how will the position of equilibrium change with a change in tempriture?
increasing the temp will increase the rate of both forward and reverse rxns but one rate will increase more than the other to oppose the increase
what is the effect of a catalyst on the position of equilibrium
it does not change the position of equilibrium it just allows equilibrium to be reached faster
what is the equilibrium constant
aA + bB <-> cC + dD
Kc = ([C]^c [D]^d) / ([A]^a [B]^b)
where:
Kc = the equilibrium constant
[C] = concentration of C
c = number of mols c
when can Kc be messured?
only when an equation is at equilibrium
what is partial pressure (of a gas in a mixture)?
the pressure a gas would have if it was alone in a container
what is the equilibrium constant Kp
it is the equilibrium constant calculated by pressure
why do we use equilibrium constant Kp instead of Kc
bc it is easier to find the pressure of a gas than the concentration of a gas
show in a formula the total pressure (of a mixture of gasses) is the sum of the partial pressures of a gas
P total = P A + P B + P C …
what is mole fraction?
it is the ratio of moles of gas to the total number of moles of gas present
what is the formula for mole faction?
mole fraction = number of mols of a particular gas / total number of mols of all the gasses in a mixture
what is the mole faction of gas A =
(n A) / (n A + n B + n C …)
where:
n = number of moles of A, B, C
how do you find the partial pressure of a particular gas in a mixture?
partial pressure = mole faction x total pressure
true or false. the sum of the mole fractions should add up to 1.00 while the sum of the partial pressure should add up to P total
True
express the equilibrium constant in terms of partial pressure
Kp = (P^c C x P^d D) / (P^a A x P^b B)
what is the Haber prosess?
a chemical reaction forming ammonia involved in the manufacture of compost
what are the factors that can effect change in equilibrium?
pressure
Temperature
catalyst
concentration
what is the only factor that affects the reaction rate but also the equilibrium constant?
Temperature
if the temperature of a reaction increases or decreases how does Kc (equilibrium constant) change?
Kc = [prod] / [reactant]
depending on which reaction is favored the products (prod) or reactants will increase causing a shift in Kc
what is the contact prosess?
it involves the synthesis of sulphuric acid (H2SO4)
what is the formula for and what ions does hydrochloric acid form?
Formula: HCl
Ions in Water: (H+) + (Cl-)
what is the formula for and what ions does nitric acid form?
Formula: HNO3
Ions In Water: (H+) + (NO3-)
what is the formula for and what ions does Sulphuric acid form?
Formula: H2SO4
Ions In Water: (2H+) + (SO4 2-)
what is the formula for and what ions does Ethanoic Acid form?
Formula: CH3COOH
Ions In Water: (H+) + (CH3COO-)
why is an organic acid weak?
because not all its hydrogens dissociate
why are stronger acids stronger?
because they have a higher concentration of Protons
what is an alkalie?
a base that is soluble in water
what is an acid according to the brownsted Lowry Theory?
a species that GIVES AWAY a proton (H+) (Ptoton Doner)
what is a base according to the bronsted lowry theory
a species that ACCEPTS a proton (H+) Using One Lone pair of Electrons (proton acceptor)
what is a Salt?
an ionic compound of a meatal and a non-meatal
what is the formula for and what ions does sodium Hydroxide form in water?
Formula: NaOH
Ions In Water: (Na+) + (OH-)
what is the formula for and what ions does potassium hydroxide form in water?
Formula: KOH
Ions In Water: (K+) + (OH-)
what is the formula for and what ions dose Aqueous Ammonia form in water?
Formula: NH3
Ions In Water: (NH4+) + (OH-)
what is dissosiation?
then a molecule breaks into ions
what is an ampolight/amphoteric substance?
a substance that can act as an acid or base depending on what it is reacting with
what occurs to make a stronger acid or base
more dissociation
i.e. equilibrium moves further to the right
what does pH equal?
- log [H+]
what makes a substance acidic?
H+ or H3O+ ions
the higher the pH of a substance the more…
basic it is
the lower the pH of a substance the more…
acidic it is
why is a weak acid or base weak?
because the substance has partially (incompletely) dissociated into ions
how can the strength of acids and bases be determined?
pH value
Electrical Conductivity
Reactivity
