Chapter 15 - Reversible Reaction Flashcards
Reversible reactions
Irreversible: Most chemical reaction are considered this (products wont readily change back into reactants)
Reversible - Can get product back to reactant
E.g heating and hydrating copper sulphate
Heating = change from blue to anhydrous white > Adding water turns white crystals blue again (hydrating them)
Open, closed, Isolated
Isolated - Flask > neither matter nor energy can escape due to vacuum
Closed - Water bottle > Matter cant escape but energy can
Open - Coffee cup > Allows energy and matter out
Dynamic Equilibrium
Equilibrium: Unchanging amount
Dynamic: reaction is still occurring
Rate of forwards reaction = rate of backwards reaction
Le chateliers principle
If a dynamic equilibrium is disturbed by changing conditions, the reaction moves to counteract the change
Things that influence a reaction: Inc/Dec the conc of substances;Changing pressure; Changing temp; changing a catalyst
Effect of catalyst: - will speed up both sides of a reaction - position of equilibrium doesn’t change
Adding/taking away substances
- By adding to one side, the reaction will add to the other side
- By subbing one side the reaction will produce more on that side
A+2B <> C + D
Adding A causes position of equilibrium to shift right to produce more C + D favouring a forwards reaction
Removing C+D causes the position of equilibrium to shift right to produce more C + D
Favouring a forwards reaction
Effect of pressure
Inc pressure > side with less molecules gets produced more
Dec pressure > Side with more molecules get produced
Effect of temp
If Temp Inc - favours endothermic reaction to bring temp down
If Temp Dec - Favours exothermic reaction to bring temp back up
Manufacturing chemicals
The Haber process
3H2 + N2 <> 2NH3 forward reaction = exo
Production of ammonia:
Made from nitrogen from air and hydrogen made from methane and water
Conditions - 450* - too low = useless
- 200atm - too high = expensive
- Iron catalyst
Compromise Conditions:
Means they are not too high (too expensive) but not too low (bad production)
If Temp Inc: Production lessens (see le chataliers principle
If pressure Inc: More ammonia production (see le chataliers principle)
Manufacturing of H2SO4
Uses - Fertilisers, manufacturing detergents (soaps hand washes) and paints Conditions: 450* 1-2 ATM V2O3 catalyst Stage 1 - S + O2 > SO2 Stage 2 - 2SO2 + O2 <> 2SO3 Stage 3 ---------- Stage 4 - SO3 + H2SO4 > H2S2O7 Stage 5 - H20 + H2S2O7 > 2H2SO4
Contact process
Stage 1: Sulfur is burned in air to make sulfur dioxide Gas
Stage 2: Sulfur dioxide is mixed with more air to make sulfur trioxide - reversible reaction
Stage 3: Gases are passed through layers of vanadium oxide catalyst at 450*
Stage 4: Sulfur trioxide added to concentration Sulphuric acid to make fuming sulphuric acid
Stage 5: Water is added to oleum to make 98% sulphuric acid