Equilibria
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Define the term dynamic equilibrium
• The forward and the backward reaction are happening at the same rate and simultaneously • So there is no net change in concentration
What conditions need to happen for equilibria to occur
It must be in a closed system
What factors effect equilibrium
• Temperature • Concentration • Pressure (only gases)
2SO2 + O2 -> 2SO3 (ΔH= -ve) What would happen to the yield of 2SO3 if temperature was increased
• Yield would decrease • The equilibrium will move the the left • Because it is the endothermic direction • So it will counter the temperature increase
2SO2 + O2 -> 2SO3 What would happen to yield of 2SO3 if pressure is increased
• Yield would increase • Equilibrium would move to the right • As it is the side with fewer gas molecules • To counter the effect of increased pressure
2SO2 + O2 -> 2SO3 What would happen to yield of 2SO3 if more oxygen is added
• Yield would increase • Equilibrium would move to the right • To decrease the concentration of O2
How would equilibrium be effected if there were same number of gas molecules on both sides and pressure is increased
There would be NO EFFECT on position of equilibrium
What are the benefits and drawbacks of using increased pressure
• May give a higher yield and will produce a faster rate • Industrially high pressure are expensive to produce
How does a catalyst work
A catalyst speeds up rate of reaction by providing an alternative reaction pathway of a lower Ea
2SO2 + O2 -> 2SO3 What would happen to yield of 2SO3 if a catalyst was used
• A catalyst increases rate of forward and backward reaction equally • So there will be no effect on position equilibrium • So yield will stay the same
What is a closed system
Using a lid or bung so no chemicals can enter or exit the system
If a reaction has a higher yield in a colder temperature is endo or exothermic
Exothermic
Write an equation for forming Ammonium Nitrate fertiliser by reacting Ammonia with a suitable acid
NH3 + HNO3 -> NH4NO3
Write an equation for forming Ammonium Sulphate fertiliser by reacting Ammonia with a suitable acid
2NH3 + H2SO4 -> (NH4)2SO4
Why is the temperature 450 degrees in the Haber process reaction
• Lower temperature gives higher yield of NH3 as forward reaction is exothermic • Higher temperature gives faster rate • Higher temperature creates large energy costs • 450oC is compromise between yield, rate and energy costs
Why is the pressure 200 atm in the Haber process reaction
• Higher pressure gives higher yield of NH3 as less gas molecules on right of equation • High pressure is very expensive (high energy cost to pressurise and equipment) • 200 atm is compromise between yield and cost