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    (Original post by Dinaa)
    PRSOM, that's great! Thank you :hugs:
    You're welcome
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    Anyone else have a chemistry mock tomorrow?
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    Doing this **** on edexcel :L.
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    Can someone help me please, how do you know that when you collect gas over water all of the gas goes through the delivery tube and some of it doesn't get stuck there. This is a question that the teacher set us.
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    (Original post by KarlLynagh)
    Can someone help me please, how do you know that when you collect gas over water all of the gas goes through the delivery tube and some of it doesn't get stuck there. This is a question that the teacher set us.
    Ya don't.

    Of course it depends on solubility. Try collecting ammonia over water and you'll be making a basic mistake...

    Damn I crack myself up...

    For many poorly soluble gasses it's fine though.
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    (Original post by Random1357)
    Ya don't.

    Of course it depends on solubility. Try collecting ammonia over water and you'll be making a basic mistake...

    Damn I crack myself up...

    For many poorly soluble gasses it's fine though.
    our teacher said there was actually a reason for it not getting stuck in the delivery tube and I can't think of any reason, nor can I find any reason.
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    (Original post by KarlLynagh)
    our teacher said there was actually a reason for it not getting stuck in the delivery tube and I can't think of any reason, nor can I find any reason.
    Not getting stuck? Thats just the pressure forcing more air through. In fact producing gas does work from a thermodynamic point of view so it can push water out the way.
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    something confusing me about sterioisomers because my textbook doesnt make it very clear...
    With E/Z isomers i get that you compare atomic numbers
    My question is do you compare the entire atomic number of the whole group to the other side...or just invidivual atoms...for example

    chlorine on one side and CH15(just an example) on the other side
    Would you do Chlorine vs Carbon...chlorine wins....then chlorine vs hydrogen...so chlorine vs 15...chlorine wins so chlorine is the highest priority
    or would you do chlorine vs the entire atomic number of ch15 which would be like 21...which would be higher than chlorine so CH15 is higher priority
    thanks for any help
    does no one know the answer?
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    (Original post by 76584)
    something confusing me about sterioisomers because my textbook doesnt make it very clear...
    With E/Z isomers i get that you compare atomic numbers
    My question is do you compare the entire atomic number of the whole group to the other side...or just invidivual atoms...for example

    chlorine on one side and CH15(just an example) on the other side
    Would you do Chlorine vs Carbon...chlorine wins....then chlorine vs hydrogen...so chlorine vs 15...chlorine wins so chlorine is the highest priority
    or would you do chlorine vs the entire atomic number of ch15 which would be like 21...which would be higher than chlorine so CH15 is higher priority
    thanks for any help
    does no one know the answer?
    I believe you go Cl v C.

    If and only if this is a tie you move to next atoms along.
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    (Original post by Random1357)
    I believe you go Cl v C.

    If and only if this is a tie you move to next atoms along.
    awesome thanks
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    (Original post by TSR Mustafa)
    Doing this **** on edexcel :L.
    Why? I'm doing Edexcel, you can PM me if you need help on anything

    Chemistry's fun
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    Okay, I was doing some Unit 1 past paper practice and I found out I don't completely understand the concept of ionic equations in Unit 1 for Edexcel Chemistry.
    You see, we weren't taught anything to do with ionic equations in Unit 1 since it made no sense in the syllabus however we were taught about ionic equations in Unit 2 and its much easier in Unit 2 than in Unit 1 as well

    I'm slightly confused when it comes to using the particular ions in the equation.
    20)
    Copper(II) sulfate solution, CuSO4(aq), can be made by adding an excess of solid

    copper(II) oxide, CuO2, to boiling dilute sulfuric acid. This is an exothermic reaction.


    The balanced equation for this reaction is

    CuO(s) + H2SO4(aq) ----> CuSO4(aq) + H2O(l)

    (a) (i) Complete the ionic equation for this reaction, including state symbols.

    CuO(s) +


    CuO(s) +

    Now, I thought you had to add everything to the equation so I put

    CuO(s) + 2H+(aq) + SO42-(aq) ----> Cu2+(aq) + SO4-(aq) + H2O(l)


    However according the mark scheme mentioning SO42- ions on either side of the ionic equation loses a mark.

    I'd get 2 marks for the following:

    CuO(s) + 2H+(aq) ----> Cu2+(aq) + H2O(l)
    I don't know how I'm meant to approach these kinds of questions. I know covalent compounds can't be ionic so they're never split up but how am I meant to know what ionic equations are meant to be used.

    This currently seems to my only major problem in Unit 1

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    (Original post by zhang-liao)
    Okay, I was doing some Unit 1 past paper practice and I found out I don't completely understand the concept of ionic equations in Unit 1 for Edexcel Chemistry.
    You see, we weren't taught anything to do with ionic equations in Unit 1 since it made no sense in the syllabus however we were taught about ionic equations in Unit 2 and its much easier in Unit 2 than in Unit 1 as well

    I'm slightly confused when it comes to using the particular ions in the equation.


    Now, I thought you had to add everything to the equation so I put

    CuO(s) + 2H+(aq) + SO42-(aq) ----> Cu2+(aq) + SO4-(aq) + H2O(l)


    However according the mark scheme mentioning SO42- ions on either side of the ionic equation loses a mark.

    I'd get 2 marks for the following:



    I don't know how I'm meant to approach these kinds of questions. I know covalent compounds can't be ionic so they're never split up but how am I meant to know what ionic equations are meant to be used.

    This currently seems to my only major problem in Unit 1

    Just quoted some people who did Edexcel according to the 1st page, any help would be much appreciated



    Simple; as a chemist I don't care about anything that isn't gonna change in my reaction. So I write my equation then cross out any compounds/ ions that DON'T change oxidation state.
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    (Original post by zhang-liao)
    Okay, I was doing some Unit 1 past paper practice and I found out I don't completely understand the concept of ionic equations in Unit 1 for Edexcel Chemistry.
    You see, we weren't taught anything to do with ionic equations in Unit 1 since it made no sense in the syllabus however we were taught about ionic equations in Unit 2 and its much easier in Unit 2 than in Unit 1 as well

    I'm slightly confused when it comes to using the particular ions in the equation.


    Now, I thought you had to add everything to the equation so I put

    CuO(s) + 2H+(aq) + SO42-(aq) ----> Cu2+(aq) + SO4-(aq) + H2O(l)


    However according the mark scheme mentioning SO42- ions on either side of the ionic equation loses a mark.

    I'd get 2 marks for the following:



    I don't know how I'm meant to approach these kinds of questions. I know covalent compounds can't be ionic so they're never split up but how am I meant to know what ionic equations are meant to be used.

    This currently seems to my only major problem in Unit 1

    Just quoted some people who did Edexcel according to the 1st page, any help would be much appreciated



    The SO42- ions are spectator ions, because they haven't changed in the reaction they're still aqueous so you cancel them out.


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    (Original post by Random1357)
    Simple; as a chemist I don't care about anything that isn't gonna change in my reaction. So I write my equation then cross out any compounds/ ions that DON'T change oxidation state.
    (Original post by ThatMadClown)
    The SO42- ions are spectator ions, because they haven't changed in the reaction they're still aqueous so you cancel them out.


    Posted from TSR Mobile
    Aaah

    So its simply due to oxidation, I feel stupid now
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    Dative covalent bonding. What is this?
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    (Original post by Dinaa)
    Dative covalent bonding. What is this?
    Well in a covalent bond you've got a shared pair of electrons holding two atoms together.

    A dative bond is where both electrons come from one atom
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    Hey, I was doing some past papers for the CHEM2 exam, and noticed I'd forgotten stuff about isomerism. Now, I think I've covered it all again, but just to make sure, are there are other types of isomerism we need to know about? (I've covered Chain, Position, Functional, Geometrical and Optical).
    Thanks
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    Anyone care to help me with a question.

    Chlorine displaces iodine from aqueous potassium iodide.

    i) Write the simplest ionic equation for this reaction.

    ii Give one observation that would make when this reactions occurs.

    Can someone explain this to me. Thanks
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    (Original post by Super199)
    Anyone care to help me with a question.

    Chlorine displaces iodine from aqueous potassium iodide.

    i) Write the simplest ionic equation for this reaction.

    ii Give one observation that would make when this reactions occurs.

    Can someone explain this to me. Thanks
    Cl2 + 2I- ----> 2Cl- + I2


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