These notes offer a comprehensive guide to the theory needed to write final exams in matric. They contain all the information on chemical equilibrium in the IEB chemistry syllabus. They are typed in a column format for easy learning. They have an array of diagrams to aid learners in their physical ...
Chemical Equilibrium
Reversible and Irreversible Referred 2 as reverse reaction.
Reactions Initially RATE of reverse reaction = 0
simply bcz no HI has formed yet.
Irreversible:
Only occur in 1 direction. As HI = formed rate of reverse
Ect sulphuric acid dehydrates sugar to reaction incr.
form black carbon: Graph Comparing Rates of
C12H22O11 (s) → 12 C (s) + 11 H2O (l) Forward & Reverse Reactions
Carbon rises in sausage shape. Water
vapour = released & escapes. Adding
water 2 black mass of carbon not
change it back 2 sweet white sugar.
Therefore irreversible.
Reversible:
CuSO4.5H2O(s) ⇌ CuSO4(s) 5H2O(l)
(pale blue solid) (“dirty” white solid)
Closed and Open Systems
Closed: no interaction btw system & W/e comparing rates = clear that as
surroundings. time progresses rates converges.
Therefore no mass may enter / leave
Dynamic Equilibrium
system.
Open: Mass may enter / leave system. Forward reaction rate = reverse
▪ Eg. A gas escaping from a flask reaction rate.
open 2 atmosphere. Then chemical equilibrium has been
reached.
Approaching Chemical Indicated by Reactants ⇋ Products.
Equilibrium There is no change of:
I2(g) react w/ H2(g) 2 form HI(g) ▪ Amount of reactant / product.
W/e H2 & I2 placed in empty container ▪ Temperature remains constant
following reaction takes plc: Equilibrium is dynamic. (even though
H2(g) + I2(g) → 2HI(g) equilibrium reached, reactions still
taking place.)
Referred 2 as forward reaction.
Equilibriums Lying ‘To Right’
Initially rate of reaction = high bcz
concentration is high. As time
progresses H2 & I2 = used, conc decr
so rate of forward reaction decr.
HI = unstable & as is formed some
immediately decomposes back into H2
and I2
2HI(g) → I2(g) + H2(g)
or
I2(g) + H2(g) ← 2HI(g)
, Equilibriums Lying ‘To Left’ Kc – Expression
For an equilibrium reaction:
aA + bB ⇌ cC + dD
Where:
Kc : equilibrium constant (no unit)
Each graph shows process reaching [Substance]: conc of reactant / prod
equilibrium in sections w/h lines = (in mol⋅dm-3)
sloping, & equilibrium that has been a,b,c,d : # of moles of each compound
reached in sections w/h the lines are in balanced reaction equation.
not sloping. Value of Kc
Compare parts of each graph w/h Economic viability of industrial process
equilibrium already reached. in chemical industry depends on
1st graph refers 2 equilibrium which manufacturing costs, product yield &
lies 2 right, & 2nd lies 2 left. retail cost.
▪ W/e lies to the right, conc of Factors determine profit co make.
products = high, relative 2 Kc values used 2 determine if possible
reactants, @ equilibrium. Each conc yield @ specific temp = low / high.
does not change over time since
rates of forward & reverse Kc is small Kc is large
(Kc < 1) (Kc > 1)
reactions are =, i.e. the system is in
equilibrium. Equilibrium conc of Equilibrium conc of
▪ W/e lies 2 left, conc of reactants = prods = low comp 2 prods = high comp 2
high, relative 2 products, @ reactants. reactants.
equilibrium. Since system in Product yield = low Product yield = high
equilibrium, each conc not change
over time (rates of forward & Industrial process Industrial process
reverse reaction =) not economically may be
Although each system’s forward & viable. economically viable.
reverse reaction rates are = @ Kc-Issues
equilibrium, not same rate as 4 other
Only use if system in equilibrium.
equilibrium setup.
Kc unit changes – no unit written.
4 1st setup equilibrium reaction rates =
Kc only constant if temp constant.
high. 4 2nd setup equilibrium reaction
Relates 2 conc - only gasses and
rates = lower.
solutions appear. (Solids & pure liquids
Equilibrium Constant (Kc) not have concentration!)
Kc = # that represents extent of how Conc of solids & pure liquids = 1.
reactants hv converted 2 products by Kc relates prods 2 reactants .
time chemical equilibrium = reached. Kc big – Lots prod, little reactants –
productive & Kc small – Lots reacts,
little prods – unproductive.
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 or Stuvia-credit 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 amywallace. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $5.77. You're not tied to anything after your purchase.
