Summary
Summary Equilibria, Haloalkanes and Alcohols
- Institution
- OCR
Equilibria, Haloalkanes and Alcohols
[Show more]
Content preview
Week 4 – Equilibria, Alcohols and HaloalkanesEquilibria
Dynamic equilibria
Reversible reactions are shown by using a reversible arrow. It looks like two arrows have been stuck on top of each other and
one side of the arrowhead has been removed.
As reactants get used up the forward reaction slows down, and more product that is formed, the reverse reaction (speeds up)
SO the rules are as reactants decrease, forwards reaction slows down. And as products increase, backwards reaction speeds up.
Dynamic equilibria = when the forwards reaction is going at exactly the same rate as the backwards reaction SO the concentration of the
reactants and the products stay constant.
Le Chatelier’s principle
As you alter the temperature, pressure or concentration the position of the equilibrium shifts… meaning different amounts of
reactants and products at equilibria.
E.g. as equilibria moves to the left you’ll get more reactants, and if it moves to the right you will get more products.
SO, Le Chatelier’s principle tells you how the position of the equilibrium will change if a condition changes.
Concentration Temperature
If you increase concentration of a reactant the If you add heat to a reaction equilibrium shifts to the
equilibrium tries to get rid of the extra so more product endothermic direction to absorb the heat.
is formed. Equilibria shifts to the right.
If you increase the concentration of a product, the
equilibrium will try to get rid of the extra so more If you decrease the temperature equilibrium shifts in
reactants are formed. Equilibria shifts to the left. the exothermic direction to try to replace the heat.
Pressure
Increasing the pressure shifts the equilibrium to the side with fewer gas molecules (to reduce pressure)
Decreasing pressure means equilibria will shift to the side with more gas molecules (to raise the pressure)
Catalysts don’t affect the position of the equilibrium. (Equilibrium reached faster, speeds up forwards and backwards by the same
amount)
Formation of Ethanol
Produced via a reversible exothermic reaction between ethene and steam.
Carried out at 300’C, 60-70atm and a phosphoric acid catalyst.
300’C is a compromise (as if you had a really low temp it would favour the forwards reaction but a really slow rate…)
BUT remember, a pressure that high is super expensive.
Kc – Equilibria constant Kp – Equilibria constant (gases)
To calculate Kc you need to do the products over the reactants Mole fraction number of moles of A / Total number of moles.
and each molecule to the power of their moles ‘a’.
SUM of mole fraction should always be equal to 1.
Kc = [A]a[B]b / [C]c [D]d
Partial pressure = the contribution that the gas makes towards
the total pressure p (A) = mole fraction of A x total pressure P
What does Kc tell us? To work out KP the equation stands the same for the calculation
of Kc.
The larger the value of Kc the further the position of the
equilibrium is to the right SO the greater the
concentration of the products compared to the
reactants. UNITS = kPa(and then you have to do some cancelling)
When Kc = 1, equilibrium is halfway between reactants Other species MUST be ignored… they are irrelevant
and products. (JUST GASES)
UNITS Cancel out what you have and don’t have etc.
Homogenous equilibria = contains equilibria species that all
have the same state or phase.
Heterogeneous equilibria = contains equilibria species that have
different states or phases (ignore solids)
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller 15watkinson. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for £7.49. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
52510 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy revision notes and other study material for 14 years now