G10 CHEM Flashcards
Reversible reactions
Both forward and the reverse reaction can occur as the product molecules can themselves react with each other or decompose and form the reactant molecules again
If the forward reaction is exothermic, the reverse will be
endothermic as the same amount of heat is transferred in both direction
Equilibirum
A system is said to be in equilibrium when the rate of forward reaction is equal to the rate of the backward reaction and the concentration of reactant and product becomes constant in a reversible reaction in a close system
More product than reactant,
Equilibrium lies to the right
More reactant than product
Equilibrium lies to the products side
Types of equilibrium
Physical and Chemical
Physical equilibrium
If there is a physical change and only the state changes
Chemical equilibrium
If there is a chemical change and new substance is formed
Example of physical equilibrium reaction
Any hydrated salt breaking down into anhydrous salt + water
Le chatelier’s principle
When a system in equilibrium is disturbed, the equilibrium wants to undo the disturbance to go back to equilibrium
What are the factors affecting equilibrium
Temp
Pressure
Concentration
Catalyst
How does a change in temperature affect the equilibrium
Increasing the temperature shifts the equilibrium to endothermic side
Decreasing the temperature shifts the equilibrium to the exothermic side
How does a change in the pressure affect the equilibrium
Increase in pressure means no of particles per unit volume increase and hence equilibrium wants to go to side with less particles. Decreasing the pressure means the equilibrium will shift to the side with more gas molecules. This is because reducing the pressure makes the system want to occupy more volume
3H_2 + N_2 ⇌ 2NH_3
where will the equilibrium shift
3 + 1 = 4 > 2
Hence equilibrium will shift in forward direction, increasing the yield of ammonia
How does a change in the concentration affect the equilibrium
Increasing the concentration of reactants/Decreasing concentration of products = equilibrium shifts in forward direction
Increasing concentration of products/Decreasing concentration of reactant = equilibrium shifts in reverse direction
How does adding a catalyst affect the equilibrium
Add a catalyst = increase rate of forward reaction and backward reaction in the same manor
Adding catalyst means equilibrium will be achieved faster, but they will have no effect in the yield of products/reactants
In an equilibrium graph, what happens to the lines of rate of forward and reverse reaction
The line representing rate of forward reaction gradually decreases before becoming constant
The line representing rate of reverse reaction gradually increase before becoming constant
What is the region called where the rate of forward and backward reactions are not constant, ie the region before equilibrium
Kinetic region
Haber’s process
industrial method for ,making ammonia (NH₃) from nitrogen (N₂) and hydrogen (H₂) gases at high pressure, moderate temperature and with a catalyst
Why is Haber process important in daily life
Haber process makes ammonia, which is an essential ingredient in the production of fertilisers, which helps grow the crops we eat
Redox Reaction
A reaction where oxidation and reduction both happen simultaneously
Conditions for oxidation to happen
1) gain of oxygen
2) Loss of electrons
3) Loss of hydrogen atoms
4) Increase in oxidation number
conditions for reduction to happen
1) loss of oxygen
2) gain of electrons
3) gain of hydrogen atoms
4) decrease in oxidation number
Who will undergo oxidation or reduction
Only reactants
Reactant which oxidises
Reductant/Reducing agent