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What are reversible reactions?
reactions where the products can react to reform the original reactants.
Equilibrium reaction
reaction that does not go to competition, reactants and products are present in fixed proportions.
What is dynamic equilibrium?
when reactants and products are constantly reacting, with the rate of the fw reaction equal to the rate of the bw reaction in a closed system. The concentrations of reactants and products remains constant.
Closed system
one in which none of reactants or products escape from the reactant mixture.
Open system
the matter and energy is lost to the surroundings.
Position of equilibrium
refers to the relative amounts of products and reactants in an equilibrium mixture.
How does changing the concentration of REACTANTS affect equilibrium?
If the concentration of reactants increases, the position of equilibrium shifts to the right to produce more products for balance.
How does changing the concentration of PRODUCTS affect equilibrium?
If the concentration of products increase, this will cause a shift in the equilibrium to the left and so more reactants are forming to reach equilibrium.
What does Le Chatelier's Principle state?
If a change is made to a system at dynamic equilibrium, the position of the equilibrium moves to minimize this change.
What is Le Chatelier’s principle used for?
to predict changes to position of equilibrium when there are changes in temperature, pressure or concentration.
How do catalysts affect equilibrium?
do not shift the position of equilibrium but speed up the rate at which equilibrium is reached.
How does increasing pressure affect the position of equilibrium?
will shift to the smaller number of molecules of gas to decrease the pressure.
How does decreasing pressure affect the position of equilibrium?
will shift to the larger number of molecules of gas to increase pressure.
How does increasing temperature affect the position of the equilibrium?
will shift to the endothermic reaction side to reverse the change.
How does decreasing the temperature affect the position of the equilibrium?
will shift to the exothermic reaction side to reverse change.
What is the equilibrium constant?
a constant calculated from the equilibrium expression for a reaction.
What does Kc mean?
This refers to the concentration constant.
What does Kp mean?
partial pressure constant.
______ are always ignored when it comes the equilibrium expression.
Solids
The Kc of the reaction is _____(1) and Kc ______(2) if __________________(3)
Specific
Changes
Temperature of reaction changes
What is the term equilibrium expression?
a simple relationship linking Kc to the equilibrium concentration / Kp to the equilibrium partial pressure of reactants and products at equilibrium taking the stoichiometry of equation into account.
What is the term partial pressure?
the pressure exerted by a particular gas A in a mixture of gases A, B, C.
How do we express equilibrium involving partial pressure?
It is involving mixtures of gases, constant (Kp) of the position of the equilibrium is used to measure the pressure than concentration.
What does the partial pressure of a gas depend on?
the number of moles of that gas in a mixture and the total pressure.
An initial, change and equilibrium table is used to…
Determine equilibrium concentration of products using the molar ration of reactants and products in the stoichiometric equation.
Regarding constant concentration and concentration changes, how would this affect the conditions?
All other conditions remain constant, Kc does not change when the concentration of reactants and products altered.
Regarding the constant concentration and pressure changes, how are the conditions affected?
All other conditions remain constant, the Kc does not change when pressure alters. There’s different number of moles are gases present
Regarding the constant concentration and temperature changes, how would it affect the position of equilibrium?
ENDOTHERMIC reaction, then there would be an increase in temperature and this would cause a shift in the reaction in the direction of the greater number of PRODUCTS.
EXOTHERMIC reaction, then there would be an increase in temperature and this would cause a shift in the reaction in the direction of the of the greater number of REACTANTS.
What are the characteristics of an endothermic reaction?
There’s a positive change in heat meaning the reaction is increasing temperature and requires a high activation energy because the energy is absorbed.
What are the characteristics of an exothermic reaction?
Within the reaction, there’s a lost in heat making it negative and requires a low activation energy because the energy is released.
What is the mole fraction?
the ratio of the moles of that gas to the total moles of gases present in the mixture.
What is partial pressure?
the pressure exerted by a particular gas A in a mixture of gases A, B, C.
How does pressure affect equilibrium?
Increasing pressure shifts equilibrium to the side with fewer gas molecules, while decreasing pressure shifts it to the side with more gas molecules.
What happens to equilibrium when temperature changes?
Increasing temperature shifts equilibrium in the endothermic direction, while decreasing temperature shifts it in the exothermic direction.
What industrial processes involves the application of equilibrium calculations?
Haber process and Contact process.
What is the Haber Process?
It involves synthesis of ammonia according to Le Chatelier’s principle.
What happens when you are changing the pressure in the Haber process?
An increase in pressure would cause a shift in the position of equilibrium towards right. High pressures are expensive to produce, so compromise pressure of 200 atm chosen. This would favor the side with the smallest molecules.
What happens when there’s a change in temperature in the Haber process?
Low temperature is required so the position of the equilibrium shifts to the right, making this a result of an exothermic reaction. The recommended temperature is 400*C-450*C because anything lower affects very low kinetic energy for particles to collide.
What happens when there’s a change in concentration in the Haber process?
There would be decreasing amount of products. Removing ammonia by condensing it to a liquid causes the equilibrium position to shift right, this would be forcing to produce more products.
What would be the catalyst in the Haber process?
Iron (Fe) would speed the rate of the reaction, behaving as a catalyst.
What is the Contact process?
It involves synthesis of sulfuric acid according to Le Chatelier’s principle.
What be used as a catalyst in the Contact process?
The contact process uses vanadium (V) oxide as a catalyst to increase the rate of reaction.
What is the recommended pressure for the contact process?
The recommended pressure is 1 atm because the partial pressure is already very high so it’s required a low pressure.
What is the recommended/suggested temperature when it comes to the Contact process?
The recommended pressure is 450*C because if the temperature lowered than the equilibrium position will shift towards the right.
What would have if there’s a change in the concentration in the Contact process?
The concentration change is the same as the Haber process, but harnessing SO3 (sulfur trioxide) to combine with the solution to produce more sulfuric acid (H2SO4).
What the difference of Acid vs Base?
Base is OH while on the other hand acid is OH+.
What is the general formula for acid base?
Acid + base → ← salt + water
What is an acid?
It neutralizes base and release hydrogen ions such as cations and anions when dissolved in water.
What are organic compounds?
Organic compounds generally contain carbon and doesn’t fully dissociate into ions.
What are inorganic compounds?
Inorganic compounds would may contain carbon and fully dissociate into ions like hyaluronic acid.
What are common acids that would appear on the exam?
HCl
HCO3
H2SO4
CH3COOH
C6H5COOH
_____(1) can dissolve in ______(2), ______(3) cannot. Not all ______(4) are ______(5) but all alkali are ______(6).
Alkaline
H2O(l)
Bases
Bases
Alkali
Bases
MEANING: Alkalines are a category under base and bases have a pH level of 7.
What are common bases that will appear on exam?
NaOH
KOH
NH3
What is the Brønsted-Lowery Theory?
This defines acids and bases in terms of proton transfer between chemical compound.
What is a Brønsted-Lowery acid?
It’s a specific species that gives away the protons within the nucleus heaving as a proton donor.
What is a Brønsted-Lowery base?
This is specific species that takes in the protons within the nucleus, behaving as a proton acceptor, using its lone pair of electrons.
What is the term amphoteric?
This term defines as species that can act both as acids and bases.
What is a strong acid?
A strong acid can almost completely dissociate into (aq) solutions.
What happens if there’s change in the equilibrium position of a strong acid?
Effecting change in the equilibrium position of strong acid effects position of equilibrium is far over to right as it is considered to be irreversible.
How are strong acid solutions are formed?
Strong acids solution formed highly acidic solutions that’s measured within the pH level of 1-3 because of high concentration of H+/H3O+ ions.
What is the formula for pH?
pH = -log10[H+ (aq)]
What is a weak acid?
It’s partially, incompletely dissociates in (aq) solutions.
If it’s a STRONG ACID where is the equilibrium position shifting to?
right
If it’s a WEAK ACID where is the equilibrium position shifting to?
Left
If it’s a STRONG ACID, how much is being dissociated?
Complete (→)
If it’s a WEAK ACID, how much is being dissociated?
Partially (→ ←)
What is the H+ concentration of a STRONG ACID?
High
What is the H+ concentration of a WEAK ACID?
low
What do you use to find the pH level of a WEAK ACID?
Use Ka to find [H+]
What are examples of STRONG ACID?
HCl, HNO3, H2SO4 (first ionization)
What are examples of a WEAK ACID?
Organic acids, e.g. ethanoic acid, HCN, H2S, H2CO3
What is a strong base?
It’s a base that dissociates almost completely in (aq) solutions.
Where does the equilibrium position shift if it’s a strong base?
Far over to the right, representing irreversible reaction
Why are strong bases highly basic?
They’re highly basic because of high concentration of OH- ions.
What is a weak base?
It’s a base that is partially dissociates in (aq) solutions.
Where does the equilibrium shift if it’s a weak base?
The equilibrium position will shift to the left so equilibrium is established.
Why are weak bases less basic?
They’re less basic because of the low concentration of OH- ions.
How are strong bases recognized? HINT: Periodic Table
Group 1 metal hydroxides
How are weak bases recognized? HINT: Periodic Table
NH3, Amines, Some transition metal hydroxides
What is a pH scale?
It’s a numerical scale that shows how acidic/alkaline a solution is (7 = neutral)
Why is the pH level of water neutral?
It dissociates into protons and hydroxide ions. The concentrations of H+ and OH- ions is very small, so the concentration of water is considered to be constant. The H2O at 298 K has equal amounts of OH- and H+ ions with concentrations of 10^-7 mol dm^-3.
Why is the pH level of acids always below 7?
Strong and weak acidic solutions always have more H+ than OH- ions. [H+] is always greater than 10^-7 mol dm^-3. So, the pH of acidic solutions is always below 7.
What are three things that are distinguishable among strong and weak basic and acidic solutions?
pH scale (through pH value)
electrical conductivity
reactivity
What is the most accurate way to determine the pH level?
pH meter
What is the least accurate way to determine the pH level?
universal indicator paper
Strong and weak acids of some concentrations react DIFFERENTLY with…
Reactive metals
What is the term neutralization reactions? HINT: general formula for ACIDS and BASES
The reactions which an acid (pH < 7) and a base (pH>7) react together to form water and salt.
What is the term spectator ion?
It is an ion which are NOT involved in the formation of water such as Na+ (aq) and Cl- (aq). These react to form salt.
What is the term titration?
This technique is used in neutralization reactions between acids and alkalis to determine the concentrations of the unknown solution.
How do you use titration?
It involves adding a titrant of known concentration from a beretta into a conical flask containing the analyze of unknown concentration.
What is the term endpoint?
It’s the equal number of moles of titrant and analyte reacting with each other, there’s no imbalance.
What is the pH level on the pH titration graph of strong acids?
pH level: 1 or 2
What is the pH level on the pH titration graph of weak acids?
pH level: 2-3
What is the pH level on the pH titration graph of strong alkalines?
pH level: 13-14
What is the pH level on the pH titration graph of weak alkalines?
pH level: 11
What is the pH level between strong acid vs strong alkai?
pH level: 7
What is the pH level between strong acid vs weak alkali?
pH level: 5.5
What is the pH level between weak acid vs strong alkali?
pH level: 9, no equivalence point
What is the term indicator?
It’s the substance that can change color when they are added to acidic/ alkaline solutions. The pH of the equivalence point, it’s very important in choosing an indicator.
What are the TWO most common indicators?
Methyl orange & Phenolphthalein
Methyl orange → pH range: 3.1-4.4
Phenolphthalein → pH range: 8.3 -10.0
Note 
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