Chemistry - Equilibrium

what type of arrows for strong acids get an why?

• single headed arrows

• they are not reversible

what type of arrows do weak acids get and why?

• double headed arrows

• they are reversible

when is chemical equilibrium achieved?

when forwards rate of reaction is equal to the reverse rate of reaction

what happens to all observable properties and concentrations of all participants when a chemical system reaches a state of equilibrium? what is happening in reality?

• become constant

• in reality, the reactions are still taking place, just at same rate

what criteria must a chemical system meet in order to be in a state of equilibrium?

1) the system must be closed

2) the observable macroscopic properties are constant

3) the reaction is sufficiently reversible so that observational properties change and then return to the original rate when a factor that affects the rate of the reaction is varies and then restored to its original value

what does it mean if a product or reactant is in the chemical equation, but not in the equilibrium equation?

that product / reactant is an intermediate

what is the first law of thermodynamics?

total energy of the universe is constant; energy cannot be created or destroyed but can only be transferred from one object or place to another, or transformed from one form to another

what does entropy state about reactions?

there is a constant drive towards chaos

what is entropy?

a measure of the randomness or disorder of a system, or surrounding

what two factors determine a reactions spontaneity? which way to reactions progress towards for each?

• enthalpy - towards minimum energy

• entropy - towards maximum chaos

what is the equation for Gibbs Free Energy?

ΔG = ΔH - TΔS

What does each value for G mean about the reaction? (-,+,0)

negative - reaction is spontaneous
positive - reaction is not spontaneous
zero - reaction is at equilibrium

for what values of H and S are the reactions ALWAYS spontaneous? (-/ +)

H = -
S = +

For what values of H and S are the reactions NEVER spontaneous? (- / +)

H = +
S = -

For what states can Equilibrium Law Equation be applied to?

Only ideal gases and solutions

What is the K_eq of the inverse of an equation?

K_eq(reverse)=1/K_eq(forward)

What is the one factor that effects K_eq?

Temperature

What does a large K_eq indicate about concentration at equilibrium?

Large [products], small [reactants]

What does a small K_eq indicate about concentration at equilibrium?

Small [products], large [reactants]

What is stress in Le Chatelier’s Principle?

any imposed factor which upsets the balance in rates between the forward and reverse reactions.

What would increasing the concentration of reactants do?

cause in increase in the [products] and decrease in [reactants]

How is a decrease in volume relieved?

System reduces the number of molecules

Which reaction does an increase in temperature favour?

Favour the endothermic reaction

Which reaction does a decrease in temperature favour?

Favours the exothermic reaction

How does catalyst shift the equilibrium concentrations?

Doesn’t shift concentrations, just causes the reaction to reach Equilibrium in a shorter period of time

what does it mean if k_trial is less than K_sp?

the solution is not saturated and no precipitate is formed

what does it mean if k_trial is greater than K_sp?

the solution is super saturated and a precipitate is formed

what does K_sp mean about the solution (saturation and precipitate)?

saturated, no precipitate