Join TSR now and get all your revision questions answeredSign up now
    • Study Helper
    Offline

    3
    ReputationRep:
    (Original post by otrivine)
    Just to inform you there is a typo i think for the K(s) + 1 1/2I2 (S) ---> KI(s)

    it should be gaseous
    I disagree because isn't that just the enthalpy change of formation and from its definition it's the enthalpy change that takes place when 1 mole of a compound is formed from its constituent elements in their standard states under standard conditions, so at room temp they are all in a solid state, surely?


    Posted from TSR Mobile
    Offline

    2
    ReputationRep:
    (Original post by MathsNerd1)
    I disagree because isn't that just the enthalpy change of formation and from its definition it's the enthalpy change that takes place when 1 mole of a compound is formed from its constituent elements in their standard states under standard conditions, so at room temp they are all in a solid state, surely?


    Posted from TSR Mobile
    Yes, well said! Iodine is a solid right and is bromine a liquid. OK let me complete the question
    • Study Helper
    Offline

    3
    ReputationRep:
    (Original post by otrivine)
    Yes, well said! Iodine is a solid right and is bromine a liquid. OK let me complete the question
    Yes, Iodine is a solid and Bromine is a liquid and okay, enjoy but now I've looked into in some more detail it doesn't seem that hard or challenging really.


    Posted from TSR Mobile
    Offline

    2
    ReputationRep:
    (Original post by MathsNerd1)
    I disagree because isn't that just the enthalpy change of formation and from its definition it's the enthalpy change that takes place when 1 mole of a compound is formed from its constituent elements in their standard states under standard conditions, so at room temp they are all in a solid state, surely?


    Posted from TSR Mobile
    answers are


    enthalpy chang eof atomisation of potassium
    standard enthalpy change of formation of KI
    1st electron affinity of iodine
    1st ionisation of potassium
    enthalpy change of atomisation of iodine

    latice enthalpy is -320Kj mol-1

    Both will be more exothermic because in sodium iodide the sodium ion has a smaller ionic radius than the potassium ion and therefore there is a stronger attraction between the Na+ and iodide ios. Calcium has a smaller ionic radius and has a greater charge density which results in a stronger electrostatic attraction between ca 2+ and I-. Calcium iodide is more exothermic than both of sodium and potassium iodide
    • Study Helper
    Offline

    3
    ReputationRep:
    (Original post by otrivine)
    answers are


    enthalpy chang eof atomisation of potassium
    standard enthalpy change of formation of KI
    1st electron affinity of iodine
    1st ionisation of potassium
    enthalpy change of atomisation of iodine

    latice enthalpy is -320Kj mol-1

    Both will be more exothermic because in sodium iodide the sodium ion has a smaller ionic radius than the potassium ion and therefore there is a stronger attraction between the Na+ and iodide ios. Calcium has a smaller ionic radius and has a greater charge density which results in a stronger electrostatic attraction between ca 2+ and I-. Calcium iodide is more exothermic than both of sodium and potassium iodide
    That's all correct, except your value for lattice enthalpy, try and check your working there.


    Posted from TSR Mobile
    Offline

    2
    ReputationRep:
    (Original post by MathsNerd1)
    Okay, here you go. (10)


    Posted from TSR Mobile
    LE= -648 kj mol-1
    • Study Helper
    Offline

    3
    ReputationRep:
    (Original post by otrivine)
    LE= -648 kj mol-1
    That is correct!


    Posted from TSR Mobile
    Offline

    2
    ReputationRep:
    (Original post by MathsNerd1)
    That is correct!


    Posted from TSR Mobile

    Define:standard enthalpy change of hydration (2)
    • Study Helper
    Offline

    3
    ReputationRep:
    (Original post by otrivine)
    Define:standard enthalpy change of hydration (2)
    The enthalpy change that takes place when 1 mole of isolated gaseous ions is dissolved in water forming 1 mole of aqueous ions under standard conditions.


    Posted from TSR Mobile
    Offline

    2
    ReputationRep:
    (Original post by MathsNerd1)
    The enthalpy change that takes place when 1 mole of isolated gaseous ions is dissolved in water forming 1 mole of aqueous ions under standard conditions.


    Posted from TSR Mobile
    Correct

    my turn
    • Study Helper
    Offline

    3
    ReputationRep:
    (Original post by otrivine)
    Correct

    my turn
    Okay, last one, each.




    Posted from TSR Mobile
    Attached Images
     
    Offline

    2
    ReputationRep:
    (Original post by MathsNerd1)
    Okay, last one, each.




    Posted from TSR Mobile
    here
    Attached Images
  1. File Type: pdf Scan0218.pdf (400.4 KB, 65 views)
    • Study Helper
    Offline

    3
    ReputationRep:
    (Original post by otrivine)
    here
    That's all correct!


    Posted from TSR Mobile
    Offline

    2
    ReputationRep:
    (Original post by MathsNerd1)
    That's all correct!


    Posted from TSR Mobile
    OK last one for today,


    a) Balance the equation
    b) Write down an expression for Kc
    c) Determine the units of Kc

    i) N2(g) + F2(g) ---> NF3(g)
    ii) NH3(g) + O2(g)---> NO (g) + H2O(g)
    iii) S(s) + O2(g) ----> SO3(g)
    • Study Helper
    Offline

    3
    ReputationRep:
    (Original post by otrivine)
    OK last one for today,


    a)Balance the equation
    b)Write down an expression for Kc
    c)Determine the units of Kc

    i)N2(g) + F2(g) ---> NF3(g)
    ii)NH3(g) + O2(g)---> NO (g) + H2O(g)
    iii)S(s) + O2(g) ----> SO3(g)
    Give me a while as I'm currently eating and just letting you know that I won't be able to revise tomorrow as I won't be in all day, going out with a few friends for the day, a meal and to see a musical so I'll see you again on Thursday, most likely.


    Posted from TSR Mobile
    • Study Helper
    Offline

    3
    ReputationRep:
    (Original post by otrivine)
    OK last one for today,


    a)Balance the equation
    b)Write down an expression for Kc
    c)Determine the units of Kc

    i)N2(g) + F2(g) ---> NF3(g)
    ii)NH3(g) + O2(g)---> NO (g) + H2O(g)
    iii)S(s) + O2(g) ----> SO3(g)
    Here we go, I hope these are correct.




    Posted from TSR Mobile
    Attached Images
     
    Offline

    0
    ReputationRep:
    (Original post by MathsNerd1)
    Was the January one hard?


    Posted from TSR Mobile
    Yes. I thought it was the hardest paper in Unit 5. I did all the past papers and it wasn't anything similar
    Offline

    0
    ReputationRep:
    I think that it is a great idea to test each other!
    • Study Helper
    Offline

    3
    ReputationRep:
    (Original post by butterflyy)
    Yes. I thought it was the hardest paper in Unit 5. I did all the past papers and it wasn't anything similar
    Oh, we'll I'm glad I didn't have to sit it then, although I'll have to sit it as my mock which won't be the best of ideas but we'll see how I do when it comes to that time.


    Posted from TSR Mobile
    • Study Helper
    Offline

    3
    ReputationRep:
    (Original post by master y)
    I think that it is a great idea to test each other!
    Want to join in next time? The more people the better, as one person could explain the concepts in a new perspective which could help out the others and vice versa.


    Posted from TSR Mobile
 
 
 
Poll
Which web browser do you use?

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Quick reply
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.