Unit 3 - Equilibria & Chemical Energy Flashcards
What does adding a reactant/ removing a product do to effect the equilibrium
- Equilibrium will shift right
- Increased concentration of products
- Favours forward reaction
What does adding a product/ removing a reactant do to effect the equilibrium
- Equilibrium shifts left
- Increases concentration of reactants
- Favours backwards reaction
How does increasing temperature affect the equilibrium
- Increasing temperature favours endothermic reaction
- Equilibrium favours direction of endothermic reaction
How does decreasing temperature effect equilibrium
- Decreasing temperature favours exothermic reaction
- Equilibrium moves in direction of exothermic reaction
Is enthalpy change positive or negative for an endothermic reaction?
Positive
Is enthalpy change positive or negative for an exothermic reaction?
Negative
What are the bewares for equilibrium concentration?
- Adding an H ion where OH is involved in reaction causes neutralisation reaction
- Adding H ion when H is involved increases concentration of opposite reaction
- Adding AgNO3 forms precipitate reactions
How does decreasing pressure effect equilibrium
- More volume
- Favours reaction which produces more gas volumes
How does increasing pressure effect equilibrium
- Less volume
- Favours reaction which produces smaller gas volumes
How does adding a catalyst effect equilibrium
Only increases the rate equilibrium is achieved
For enthalpy of combustion questions, are answers positive or negative
Negative
State Hess’s law
The enthalpy change of a chemical reaction is independent of the route taken
Are breaking bonds endothermic or exothermic
Endothermic (+ve)
Are making bonds endothermic or exothermic
Exothermic (-ve)
What’s the formula for enthalpy change for bond enthalpy questions
🔺H = Bonds Broken(+ve) + Bonds made (-ve)
What is the difference between bond enthalpy and mean bond enthalpy
- Molar bond enthalpy is the energy required to break one mole of bonds in a diatomic molecule.
- Mean molar bond enthalpy is the average energy required to break one mole of bonds that occur in compounds. (Must write average for full marks)
What happens if you add lime water to an equation featuring CO2 as a reactant?
Eg. Adding lime water to this equation: CO2 + O2 ↔️ H2O
Lime water removes CO2. Equilibrium shifts left to create more CO2.
What happens if you add an ion to a chemical reaction featuring a metal ion?
If you add an ion that will form a precipitate with the metal ion, (check solubility table) it will remove it from the system.
What happens if you add a silver ion to a halide ion (eg. Cl-) ?
It will form a precipitate and remove the halide ion from the system.
