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    (Original post by Ecstacy.)
    Zn ---> Zn2+ + 2e (-0.76)
    if you increase the concentration of Zn2+, euilibrium shifts to the LHS.
    Why does the whole cell potential be lower?

    Cu2+ + 2e ---> Cu (+0.34)
    increasing Cu2+, it shifts to the RHS
    why is the whole cell potential higher?

    is the end point of manganese and iron titration from colourless to the first hint of permanent pink?

    if someone can help me with that, thank you.
    For the first half cell, under non-standard conditions (in this case) if you increase the conc of Zn2+ then the electrode potential will be less negative due to the fact Zinc is being reduced and using up electrons.

    The whole cell potential is the positive terminals' standard electrode potential - the negatives terminals' standard electrode potential. Therefore here we have:-

    +0.34 - (-0.76) = +1.1v.



    Regarding the colour change I think its from purple to almost colourless (pale pink).
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    can somone please explain free energy to me? I don't fully understand it.

    Never mind.
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    2nd electron affinity is positive becuase the ions and the electrons are both negative and so energy is needed to overcome the repulsion!
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    (Original post by SmartFool)
    Quick question, do you put h20 in kc equilibrium and kstab or not? Someone answer please!
    put it in kc but not kstab
    in kstab it is in excess so it is not needed in the equation
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    (Original post by sportycricketer)
    Is the colour change for MnO4/Fe equilibrium from dark purple to pale pink??
    No its purple to colourless
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    You're adding another electron to the same shell and so energy must be put in to overcome the electron repulsion.
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    some please explain the indicators for titrations!
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    could somebody explain spontaneous reactions (like the whole thing about T^S being greater than ^H or something), i dont quite get it?
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    (Original post by volvicstar)
    some please explain the indicators for titrations!
    A suitable indicator is one which changes colour within the pH range in the vertical section of a titration curve. The pH of a suitable indicator should be as close as possible to the pH of the equivalence point (which is when vol of acid added = vol of base added).

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    (Original post by gkaur123)
    could somebody explain spontaneous reactions (like the whole thing about T^S being greater than ^H or something), i dont quite get it?
    ^G<0
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    Lets do this!!
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    (Original post by gkaur123)
    could somebody explain spontaneous reactions (like the whole thing about T^S being greater than ^H or something), i dont quite get it?
    Basically a spontaneous endothermic reaction can occur if:
    • If the temperature is high enough that T^S is higher than ^H so when put in the equation, ^G will be negative, thus a reaction is feasible.
    • ^S is positive- so if there's an increase in entropy
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    Buffer solutions are made of a weak acid and the salt of the weak acid. The salt dissociates to give large amounts of the conjugate base.

    If any acid is added (H plus ions) then it will be removed by the conjugate base shifting equilibrium to the left. This reduces the concentration of H plus ions.

    If a base is added then it removed by the acid. The equilibrium shifts to the right increading conentration H plus ions.

    You could think of it like this Acid = H plus + base
    if more h plus are added the way to remove them is by shifting equilibrium to left to give more acid and less h plus ions.

    hope that helps
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    do we have to know what a tetrahedral complex ion looks like?
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    (Original post by Wilzyy)
    Basically a spontaneous endothermic reaction can occur if:
    • If the temperature is high enough that T^S is higher than ^H so when put in the equation, ^G will be negative, thus a reaction is feasible.
    • ^S is positive- so if there's an increase in entropy
    oooh, okay! thankyou! good luck
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    (Original post by Rudeboy999)
    Buffer solutions are made of a weak acid and the salt of the weak acid. The salt dissociates to give large amounts of the conjugate base.

    If any acid is added (H plus ions) then it will be removed by the conjugate base shifting equilibrium to the left. This reduces the concentration of H plus ions.

    If a base is added then it removed by the acid. The equilibrium shifts to the right increading conentration H plus ions.

    You could think of it like this Acid = H plus + base
    if more h plus are added the way to remove them is by shifting equilibrium to left to give more acid and less h plus ions.

    hope that helps
    why does the salt dissociate?
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    in aqueous solution the salt dissociates to Na plus and the base. This is like NaOH dissociates to Na+ and OH minus

    hope that helps
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    what is e.m.f??
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    (Original post by volvicstar)
    why does the salt dissociate?
    Cause they said so. xD.
    Lol, no just joking, they won't ask but I imagine its something to do with enthalpy change of solution/hydration of the salt's ions.
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    (Original post by Perky perks)
    what is e.m.f??
    it is the voltage when no current flows
 
 
 
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