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    Chem help..... :O

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    The Banker
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    Chem help..... :O

    Post by The Banker on Thu Nov 19, 2009 6:50 pm

    ok...
    what is a dative covalent bond??
    i've looked through all my books, asked my teachers... etc.
    and didn't get a straight answer..
    can u guyz help????
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    Ahmed
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    Re: Chem help..... :O

    Post by Ahmed on Thu Nov 19, 2009 8:07 pm

    Dative covalent bond is a description of covalent bonding between two atoms in which both electrons shared in the bond come from the same atom.


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    Re: Chem help..... :O

    Post by The Banker on Thu Nov 19, 2009 8:16 pm

    ohhhh
    so one atom sharez its electronz with the other atom and the aother atom doesn't want to share its electronz??
    like NH4????
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    Re: Chem help..... :O

    Post by Ahmed on Thu Nov 19, 2009 8:22 pm

    NH4+ is ionic...not covalent. It is an exception Wink. It acts like an ionic compound.


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    Re: Chem help..... :O

    Post by The Banker on Thu Nov 19, 2009 8:29 pm

    ahhhhhhhhhhhhh!!
    i'm confuzzled man!
    explain plz... Sad
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    Re: Chem help..... :O

    Post by Ahmed on Thu Nov 19, 2009 8:32 pm

    Covalent compounds usually have a negative net charge. NH4+ has a positive net charge. Therefore it acts as if it's a ionic compound (which have positive charges)

    Covalent compounds are like:

    SO4^-2
    ClO3^-


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    Re: Chem help..... :O

    Post by The Banker on Thu Nov 19, 2009 8:37 pm

    kk
    thanx ahmed...
    ur a BIG help
    Smile
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    Re: Chem help..... :O

    Post by Ahmed on Thu Nov 19, 2009 8:38 pm

    No Prob.

    I have a chem test tomorrow :S

    Make Du3aa for me PLEASE!!


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    Re: Chem help..... :O

    Post by The Banker on Thu Nov 19, 2009 8:40 pm

    kk
    inshaAllah man..
    Smile
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    Re: Chem help..... :O

    Post by Doc on Sat Nov 21, 2009 4:37 am

    so how was it?

    insha'Allah you'll get an A

    and a covalent bond is a bond between nonmetallic atoms where electrons are shared ...
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    Re: Chem help..... :O

    Post by Ahmed on Sat Nov 21, 2009 2:20 pm

    I am so happy, thank you all or you du3aas, I think they helped me a lot. I might have even gotten 100% Allahu A23lam, but I found it to be the test that I did the best on. Maybe beacause thsi time I actually studied lol? Razz


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    Re: Chem help..... :O

    Post by Egyptian Gazelle on Sat Nov 21, 2009 2:48 pm

    Sultan Ahmed IV wrote:I am so happy, thank you all or you du3aas, I think they helped me a lot. I might have even gotten 100% Allahu A23lam, but I found it to be the test that I did the best on. Maybe beacause thsi time I actually studied lol? Razz

    WOW! Thats good l7l....I bet you got a 100 haha
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    Re: Chem help..... :O

    Post by Ahmed on Sat Nov 21, 2009 4:52 pm

    The Egyptian Gazelle wrote:
    Sultan Ahmed IV wrote:I am so happy, thank you all or you du3aas, I think they helped me a lot. I might have even gotten 100% Allahu A23lam, but I found it to be the test that I did the best on. Maybe beacause thsi time I actually studied lol? Razz

    WOW! Thats good l7l....I bet you got a 100 haha

    Thanks Reem Razz


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    Re: Chem help..... :O

    Post by Egyptian Gazelle on Sat Nov 21, 2009 4:52 pm

    np
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    Re: Chem help..... :O

    Post by The Banker on Sat Nov 21, 2009 8:28 pm

    Sultan Ahmed IV wrote:I am so happy, thank you all or you du3aas, I think they helped me a lot. I might have even gotten 100% Allahu A23lam, but I found it to be the test that I did the best on. Maybe beacause thsi time I actually studied lol? Razz

    alhamdullilah u found it easy man.... i actually made duaa 4 u..
    now u have 2 make duaa 4 me coz i have a chem test on thursday... Very Happy
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    Re: Chem help..... :O

    Post by The Banker on Sat Dec 19, 2009 5:28 pm

    emm ok ppl i really need help :S

    >> Q) Sodium burns in excess Oxygen to give the solid, Y.
    a) Y contains 58.97% Sodium. Find the emperical formula.

    this is how i worked it out..
    100-58.97= 41.03
    so there is 41.03% Oxygen in Y
    Sodium: 58.97/23 =2.56 moles

    Oxygen: 41.03/16 =2.56 moles
    and so Sodium : Oxygen = 1:1
    so the emperical formula is NaO
    b) The relative molecular mass of Y is 78. What is the molecular formula?
    Mr of NaO:: (23x1)+(16x1) = 39
    78/39 =2
    2(NaO)
    = Na2O2
    ==================================================================
    i have a feeling this is all wrong... i need someone to check it for me.
    thanx
    Smile
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    Re: Chem help..... :O

    Post by Steve on Sat Dec 19, 2009 5:30 pm

    the answer is always X = 2

    its because burried treasure is always under a big 2 Smile
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    Re: Chem help..... :O

    Post by Ahmed on Sat Dec 19, 2009 5:37 pm

    Darn I did this like 2 months ago. Anyways...

    Yes they are both correct.


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    Re: Chem help..... :O

    Post by The Banker on Sat Dec 19, 2009 5:41 pm

    Ahmed IV wrote:Darn I did this like 2 months ago. Anyways...

    Yes they are both correct.
    yh... i did this right at da begining of da year...
    i'm revising 4 my real exam which is in 2 weeks :S
    and i like ur new profile pic by da way... Wink


    @Steve:: ahhh stop confusing me man!! Razz
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    Re: Chem help..... :O

    Post by Steve on Sat Dec 19, 2009 5:42 pm

    but ahmed said we were both correct Razz
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    Re: Chem help..... :O

    Post by Ahmed on Sat Dec 19, 2009 5:43 pm

    Well if you want to be 100% precise when dividing by the molar
    mass of the Oxygen and Sodium you should divide by up to 4 sig figs.
    The answer is still the same though. Wink

    P.S.: Thanks, ii was my first profile, before any Y!A members were here...I missed it so I got it back Smile


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    Re: Chem help..... :O

    Post by The Banker on Sat Dec 19, 2009 6:33 pm

    Q)
    a) what is the enthalpy chnage for the following reaction?
    2C(graphite) +2H2 + O2 ========> CH3COOH

    enthalpies of combustions:-
    C = -394
    H2 =-286
    CH3COOH = -874

    i'm totally baffed... ?!??!?! :S
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    Re: Chem help..... :O

    Post by Ahmed on Sat Dec 19, 2009 6:35 pm

    Simple:

    [Enthalphy of Products]-[Enthalphy of Reactants]

    But wait, why does C and H2 have an enthalpy?? Could you give me their states? (solid,liquid, gas)


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    Re: Chem help..... :O

    Post by The Banker on Sat Dec 19, 2009 6:37 pm

    C is solid
    H is gas
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    Re: Chem help..... :O

    Post by Ahmed on Sat Dec 19, 2009 6:41 pm

    Those values are the enthalpies of formation, correct?


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