C5- How Much Part 2

C5- How Much Part 2

1. Equlibrum

   • a reverisable reaction is one where the products of the reactants can themselves react to produce the orginal reatants
   • as reactants A and B react their concetraions fall - so the foward reaction will slow down but as more products C and D are made their concetraions rise and the backward reaction speeds up
     • after a while the forward reaction will go at the same rate as the backwards this is equblrium
       • there is no overall effect as the concetraions of the reactants have reached a balance and won't change
         • Equlbrium can only be reached in a closed system. a closed system means that no of the products and reactants can escape
   • Postion of eqlubrium
     • when it lies to the right there is lots of products and not much of the reactants
     • when it lies to the left this means lots of reactates and not much of the products
     • 3 things can change the postion of the equbrium
       • Temperature
       • Pressure only effects gases
       • concentration
       • add a catylst only speeds up the reaction it does not effect the equlbrium

2. Changeing equlibrum

   • Temperature
     • 1) if you decrease the temperature, the equbilbrum will move and try and increase it - the equlbrium moves in the exothermic direction to produce more heat it moves to the left
       • 2) if you raise the tempeartue the equlbrium will move to try to decrease it - it moves to an endothermic reaction to the right
   • Pressure only with gases
     • 1) if you increase the pressure the eqlubrium will try to reduce it moving in the direction where there is fewer gases moles
       • 2) if you decrease the pressure the equlbrium tries to increase it - it moves in the direction where there is more moles of gas
   • Concentraion
     • 1) if you increse the concetrion of the reaction by adding more A and B the equlbrium tries to deacrese it by moving into the right making more C and D
       • 2) if you increase the concentration of the product by adding more C + D the eqlbrium tries to reduce it by shifting to the left producing more A+B
   • you need to be able to interpt data

3. The contact process

   • 1) the frist stage is to make sulphur dioxide
     • 2) sulfur dioxide is oxidsied to make sulphur trioxide
       • 3) the sulphur trioxidr is used to make sulprhic acid
   • the condtions to make sulphric acid are carefull chosen
     • Condtions are carefuly chosen

4. Strong and weak acids

   • Strong acids ionsie complety this means loads of H+ ions realsesd
     • Weak acids do not fully ionise ony a small number of H+ ions realsied
   • Concetration of acid is differnt to strength
     • Concetraion is how many moles of acid are in 1dm cubes of water. concetraion is basicaly how watered down the acid is.
       • so you can have a dillute but strong acid or a concetrated weak acid
   • Acids produce H+ ions when the ionise
   • Strong acid are better electrical conducters then weak acids
     • High concetraion of ions in the strong acid means the more charge can be carried
       • Low concetrion of ions in weak acid means that less charge can be carried
   • Stronger acids react faster then weaker acids
     • in a weaker acid there a less H+ atom so the collsion frequency is low
       • this deacrease the rate of reaction
     • In stronger acids the is more H_ atom so the collsion frequency is high
       • This increase the rate of reaction
     • this reason for this is that stronger acids let go of the H+ ion all at once wheas weaker acid let go of them gradualy
   • Rate of reaction will change if differnt volumes are used

5. Precipitation reactions

   • Precitaion reacts invove two soloitions reacting toghtear to form an insoube substance
     • this substance is called a pericpate and turns the soultion cloudy
       • Most of these reactions involve ions to react with each other they need to be able to move
         • this means they have to be in souloution so that they can move
           • the reaction is usaluy extermly quick because there is high collsion frequency between ions
   • IOnic equations
     • Aq stand for aquas which means dissoved in water
     • in an ionic eqyation give the reacting section
     • you can tell its a perction because you have 2 soultions and you get a soild

6. Preparing in souble salts

   • you need ions to make an inosuble salt
     • This is the eqaution used but if you just do this the salt will be wet
       • So you must prapare it

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