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    (Original post by Shadowfire123)
    which forces
    van der waals
    hydrogen bonds
    and dipole dipole
    Dipoles dipoe and vdw please
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    why are mean bond enthalpy values different
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    (Original post by MikaHina)
    Please can someone help me with (ii) I'll be forever in your debt and I would send you food if I could ! Attachment 405317
    Delta H = Q/n

    1.15kj / 0.01 = -115kj

    ...I'll happily take a dominoes
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    (Original post by Dyl98an)
    Also if you have 2 bond pairs and 2 lone pairs. Do they cancel to form a linear shape?
    If not then what happens?
    no the shape is non linear. you just have to learn it. the bond angle would be 104.5
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    (Original post by Dinaa)
    why are mean bond enthalpy values different
    Its an average number of the enthalpy value that varies in a bond.

    You'd think its same, but when you break one bond, e.g. on CH4, it changes the environment for the remaining bond, decreasing their bond enthalpy. (Extra repulsion)
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    (Original post by itsConnor_)
    Why does solubility of hydroxides increase down the group ? And why does the ease of thermal decomposition of carbonates decreases down the group ?
    you don't need to know why they just do.
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    (Original post by Dyl98an)
    You see when there's 2 bond pairs and 1 lone pair (bent shape) is the angle 177.5 or 117.5?
    117.5
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    Can anybody explain the oxidation state of this P in this reaction, I totally don't get it.
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    (Original post by NotoriousS)
    Delta H = Q/n

    1.15kj / 0.01 = -115kj

    ...I'll happily take a dominoes
    You my friend, are an absolute life saver, so for for those types of questions in general, you turn the energy transfer in to KJ and then divide by the moles ? and why is the value negative -if you don't mind me asking !

    Dominoes is a good choice -I have it on speed dial during revision xD
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    (Original post by MikaHina)
    You my friend, are an absolute life saver, so for for those types of questions in general, you turn the energy transfer in to KJ and then divide by the moles ? and why is the value negative -if you don't mind me asking !

    Dominoes is a good choice -I have it on speed dial during revision xD
    You could use either joules or Kj, and I presumed that the reaction was exothermic as energy is mostly given out by the bonds made and my bad, the units are Kj/mole
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    (Original post by NotoriousS)
    You could use either joules or Kj, and I presumed that the reaction was exothermic as energy is mostly given out by the bonds made and my bad, the units are Kj/mole
    Surely the answers would be different then ? or does it not matter as long as your units are correct ? ah no that's right don't worry ! and I thought so too, thank you so much again !
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    (Original post by Dyl98an)
    Also if you have 2 bond pairs and 2 lone pairs. Do they cancel to form a linear shape?
    If not then what happens?
    That's bent also
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    (Original post by Mehrdad jafari)
    Can anybody explain the oxidation state of this P in this reaction, I totally don't get it.
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    Hi I'll try make it simple
    In P4 it's 0 like you've wrote as it's an element

    In PH3 - you know H is +1 so +1 x3 = +3. To cancel the charge P must equal to -3

    In NaH2PO2 - you know Oxygen = -2
    -2x2= -4
    H2 +1 x 2 = +2
    -4 + +2 = -2
    Na is in group one so +1
    -2+ +1 = -1 in P

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    (Original post by samwillettsxxx)
    Hi I'll try make it simple
    In P4 it's 0 like you've wrote as it's an element

    In PH3 - you know H is +1 so +1 x3 = +3. To cancel the charge P must equal to -3

    In NaH2PO2 - you know Oxygen = -2
    -2x2= -4
    H2 +1 x 2 = +2
    -4 + +2 = -2
    Na is in group one so +1
    -2+ +1 = -1 in P

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    Thank you very much! I had difficulty with the oxidation of hydrogen in PH3 because i though the oxidation state of hydrogen should be negative as it's more electronegative than P which put me into trouble
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    (Original post by Mehrdad jafari)
    Thank you very much! I had difficulty with the oxidation of hydrogen in PH3 because i though the oxidation state of hydrogen should be negative as it's more electronegative than P which put me into trouble
    You're welcome.. Hope it was easy to understand
    Hydrogen is always +1 just remember that
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    (Original post by samwillettsxxx)
    You're welcome.. Hope it was easy to understand
    Hydrogen is always +1 just remember that
    yeah, it definitely was. I will never forget that
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    can anyone help me on cracking of alkanes please?? like thermal cracking and catalytic cracking.
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    (Original post by Lilmissy345)
    can anyone help me on cracking of alkanes please?? like thermal cracking and catalytic cracking.
    Thermal cracking is at high pressure and temps and makes high yield of alkenes

    Catayltic cracking uses a zeolite catalyst and makes a high yield of alkenes/branched alkanes good for motor fuels
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    (Original post by samwillettsxxx)
    Thermal cracking is at high pressure and temps and makes high yield of alkenes

    Catayltic cracking uses a zeolite catalyst and makes a high yield of alkenes/branched alkanes good for motor fuels
    wow thankkss sooo much
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    (Original post by Lilmissy345)
    wow thankkss sooo much
    You're welcome
 
 
 
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