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    (Original post by Bennyh2k9)
    I made 1 definite silly mistake and it was accidently doing a covalent dot and cross diagram instead of ionic
    What mistakes have you made?
    OMG I DID THAT!!!! SO ANNOYED WITH MYSELF!!! Two marks gone >
    Think we can get marks for showing the correct number of electrons haha?
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    (Original post by Marli-Ruth)
    OMG I DID THAT!!!! SO ANNOYED WITH MYSELF!!! Two marks gone >
    Think we can get marks for showing the correct number of electrons haha?
    nope lol one mark will be for both identifying that 2 electrons will be transfered and for realising it is ionic. The second mark will be for the correct charges. i think
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    Q1.
    14, 14, 14
    14, 15, 14,
    14, 16, 14 [1]

    Ionisation
    Acceleration
    Drift [1]

    KE [3]

    72.7 [2]

    1.8-2? [2]

    Double beta decay of Germanium to Selenium [2]

    Protons/neutrons/electrons charge/mass [1]

    electronic structure of germanium [1]
    Why did Mendeleev leave gaps? [1]
    what period and group tells us: period = amount of shells, group = valence shell number of electrons [2]

    Q2?. ...
    Enthalpy change of decomposition of H2O2 = -196 kJMol^-1 [2]
    Formation of water equation
    ?
    Volume of products = 277/288/289? [3]
    H2O2 = easily combustible due to oxygenated? / doesn't produce carbon emissions? [1]

    Q3.
    How is an oxide of nitrogen made in exhaust fumes?

    Explain bond enthalpy and why it is an average: bond enthalpy is then enthalpy needed to break 1 mole of gaseous compounds [2]
    Reforming and hydrogen [1]
    C-C-C bond in cyclopropane: 109 because 4 regions of electron density around central C atom but in truth 60 degrees [4]
    Significance of a wedge [1]
    Zeolite is used as a catalyst [1]

    Q4
    Silicon and calcium are in the same group so share similar properties [1]
    Ionic silicon oxide [2]
    Emission spectra
    Constants in experiment: mass/moles of carbonate, same heating conditions, volume of limewater [2]
    what happens to the limewater? turns cloudy white and fizzes/effervesces on presence of CO2 [2]
    Silicate ion SiO32-

    have fun amending or adding or changing or whatever
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    (Original post by HecTic_H)
    Q1.
    14, 14, 14
    14, 15, 14,
    14, 16, 14 [1]

    Ionisation
    Acceleration
    Drift [1]

    KE [3]

    72.7 [2]

    1.8-2? [2]

    Double beta decay of Germanium to Selenium [2]

    Protons/neutrons/electrons charge/mass [1]

    electronic structure of germanium [1]
    Why did Mendeleev leave gaps? [1]
    what period and group tells us: period = amount of shells, group = valence shell number of electrons [2]

    Q2?. ...
    Enthalpy change of decomposition of H2O2 = -196 kJMol^-1 [2]
    Formation of water equation
    ?
    Volume of products = 277/288/289? [3]
    H2O2 = easily combustible due to oxygenated? / doesn't produce carbon emissions? [1]

    Q3.
    How is an oxide of nitrogen made in exhaust fumes?

    Explain bond enthalpy and why it is an average: bond enthalpy is then enthalpy needed to break 1 mole of gaseous compounds [2]
    Reforming and hydrogen [1]
    C-C-C bond in cyclopropane: 109 because 4 regions of electron density around central C atom but in truth 60 degrees [4]
    Significance of a wedge [1]
    Zeolite is used as a catalyst [1]

    Q4
    Silicon and calcium are in the same group so share similar properties [1]
    Ionic silicon oxide [2]
    Emission spectra
    Constants in experiment: mass/moles of carbonate, same heating conditions, volume of limewater [2]
    what happens to the limewater? turns cloudy white and fizzes/effervesces on presence of CO2 [2]
    Silicate ion SiO32-

    have fun amending or adding or changing or whatever
    If for the reforming question i put hydrogen gas instead of just hydrogen will i not get the mark?
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    Name:  image.jpg
Views: 274
Size:  77.2 KB Why is the answer to this -82 x 2 = -164
    But in our exam today it wasn't simply multiplying the number of formation for hydroxide by 2?
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    Paper was about the same difficulty as last year. Expect 48 max. Wouldn't be surprised if it was 45. Lots of places to drop silly marks like last year.
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    (Original post by Marli-Ruth)
    Name:  image.jpg
Views: 274
Size:  77.2 KB Why is the answer to this -82 x 2 = -164
    But in our exam today it wasn't simply multiplying the number of formation for hydroxide by 2?
    Omg where did you get that paper from??


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    (Original post by Supergirlxxxxxx)
    Omg where did you get that paper from??


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    May 2010 xx
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    (Original post by Jam3898)
    Paper was about the same difficulty as last year. Expect 48 max. Wouldn't be surprised if it was 45. Lots of places to drop silly marks like last year.
    I agree
    Think it will be 45
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    Lol that's so unrealistic, it's gonna be 52


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    I'm pretty sure the answer to the enthalpy change when H2O2 decomposes was -98 kJmol^-1... The question gave the standard enthalpy of formation of H2O2 and H2O, but the equation they gave had 2 moles of each. The standard enthalpy of formation is the enthalpy change when 1 mole of product is formed, therefore you had to half the answer, or rewrite the equation so that there was one mole of each first (Look at the CGP revision book, page 35; they half their answer due to there being 2 moles).

    Anyway it will be 1 mark for the answer and 1 mark for the sign, so no big deal really, but if anyone wants to ask their teacher that'd be great.
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    Enthalpy change would be -98 for one mole surely?

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    (Original post by HT12345)
    I'm pretty sure the answer to the enthalpy change when H2O2 decomposes was -98 kJmol^-1... The question gave the standard enthalpy of formation of H2O2 and H2O, but the equation they gave had 2 moles of each. The standard enthalpy of formation is the enthalpy change when 1 mole of product is formed, therefore you had to half the answer, or rewrite the equation so that there was one mole of each first (Look at the CGP revision book, page 35; they half their answer due to there being 2 moles).

    Anyway it will be 1 mark for the answer and 1 mark for the sign, so no big deal really, but if anyone wants to ask their teacher that'd be great.
    ^ we posted at the same time. I agree. Good to know I got a mark where sooo many slipped up

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    I'm pretty sure it was -196 for the enthalpy change of decomposition, our chemistry teacher looked it up on the Internet to double check
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    The average for an A has been 49 or so, never that high. Doesn't matter you easy you personally might have found the paper

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    (Original post by Atl101)
    I'm pretty sure it was -196 for the enthalpy change of decomposition, our chemistry teacher looked it up on the Internet to double check
    Why would your chemistry teacher look something like this up when they could calculate the answer given the facts?

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    (Original post by vuvuzela)
    Why would your chemistry teacher look something like this up when they could calculate the answer given the facts?

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    Sorry should of made that more clear, they calculated the answer and then double checked it on the internet
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    Found the answer! http://en.wikipedia.org/wiki/Hydrogen_peroxide Under reactions, the enthalpy change is -98 kJmol^1 Seems more than coincidence that I got the same value in the exam, so they haven't given us random numbers.
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    (Original post by Atl101)
    Sorry should of made that more clear, they calculated the answer and then double checked it on the internet
    They is wrong fo' sho'
    Deffo -98

    2H2O2------> 2H2O + O2



    Delta Hf of 1 mole of H2O2 = -188
    Delta Hf of 1 mole water = -286

    -(-188)+(-286) = -98KJmol^-1

    Your teacher is not good


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    It said calculate enthalpy change of reaction not of formation of h2o.


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