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  1. [1]
    أبوبكرمصطفى
    أبوبكرمصطفى غير متواجد حالياً

    عضو فعال

    تاريخ التسجيل: May 2006
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    طلب معلومة

    الاخوة الاعضاء
    السلام عليكم ورحمة الله وبركاته
    أنا في حوجة ماسة وعاجلة لمعرفة قيم الخواص الاتية لمركب اليوريا (NH2CONH2 ):
    1-اللزوجة (viscosity ).
    2-الكثافة (density ) .
    3-المصلية الحرارية(Thermal Conductivity ).
    وذلك عند درجة الحرارة 110درجة مئوية.
    وكان الله في عوننا جميعا.

  2. [2]
    أبوبكرمصطفى
    أبوبكرمصطفى غير متواجد حالياً
    عضو فعال


    تاريخ التسجيل: May 2006
    المشاركات: 92
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    الاخوة الاعضاء
    السلام عليكم ورحمة الله وبركاته
    أنا في حوجة ماسة وعاجلة لمعرفة قيم الخواص الاتية لمركب اليوريا (NH2CONH2 ):
    1-اللزوجة (viscosity ).
    2-الكثافة (density ) .
    3-المصلية الحرارية(Thermal Conductivity ).
    وذلك عند درجة الحرارة 110درجة مئوية.
    وكان الله في عوننا جميعا.
    عفوا أرجو المراسلة علي البريد الالكترونى:
    abubakrmstf***********

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  3. [3]
    الكيميائى الحر
    الكيميائى الحر غير متواجد حالياً
    عضو


    تاريخ التسجيل: May 2006
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    General

    • Synonyms: B-I-K, carbamide, carbamide resin, carbamimidic acid, carbonyl diamide, isourea, pseudourea, carbonyldiamine, supercel 3000, ureaphil, ureophil, urevert, varioform II
      Molecular formula: CH4N2O
      CAS No: 57-13-6
      EC No: 200-315-5
    Physical data

    • Appearance: white crystalline powder
      Melting point: 135 - 137C
      Boiling point:
      Specific gravity: 1.335
      Vapour pressure:
      Flash point:
      Explosion limits:
      Autoignition temperature:
      Water solubility: moderate
    Stability

    • Substances to be avoided include strong oxidizing agents. Protect from moisture.
    Toxicology

    • Not hazardous according to Directive 67/548/EEC.
      Toxicity data
      (The meaning of any abbreviations which appear in this section is given here.)
      ORL-RAT LD50 8471 mg kg-1
      IPR-RAT LD50 > 5000 mg kg-1
      IVN-RAT LD50 5300 mg kg-1
      IVN-MUS LD50 4600 mg kg-1
      Risk phrases
      (The meaning of any risk phrases which appear in this section is given here.)
    Personal protection

    • Minimize exposure. Safety phrases
      (The meaning of any safety phrases which appear in this section is given here.)

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  4. [4]
    الكيميائى الحر
    الكيميائى الحر غير متواجد حالياً
    عضو


    تاريخ التسجيل: May 2006
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    [MOVE="left"]
    Identifiers,Physical and Chemical properties 1
    CAS Number :57-13-6
    End Point :IDENTIFIERS,PHYSICAL AND CHEMICAL PROPERTIES
    Substance
    Chemical Name :Urea
    Common Name :Urea
    RTECS Number :YR6250000
    Properties &Definitions
    Molecular Formula :CH4N2O
    Molecular Weight :60.06
    Melting Point :133C*
    Boiling Point :135C decomposition**
    State :Crystal prismatic or powder
    Flamable Limit :Non-flammable
    Density :1323 kg/m3 at 20-24C
    Vapour Pressure :80 Pa (0.6 mmHg)at 20C CAL***
    Octanol/Water Partition :
    Coefficient
    -1.59 at 20-25C experimental
    Water Solubility :1080 g/L at 20C
    Solubility in other :
    Solvents
    10 g/L in 95%alcohol,167 g/L in methanol,500 g/L in glycerol
    Colour :Colourless to white
    Taste :Cooling,saline
    Odour :Almost odourless
    Additives :Urea-formaldehyde binder can be used in some prilling processes.
    Impurities :Biuret 0.3 -2 wt%;cyanates.Analysis of technical urea gave the
    followings:water (as moisture)0.4 wt%;free ammonia 0.4 wt%;Fe
    2+<0.0002 wt%;ash content <0.02 wt%.Degree of purity 98-99
    wt%.
    General Comments :*On further heating decomposes to biuret,NH3 and cyanuric acid.On standing
    or on heating decomposes to NH3 and CO2.**Urea decomposes before
    boiling.***VP of saturated water solution=2kPa at 20C.Hypochlorites can react
    with urea to form the explosive compound,nitrogen trichloride.Reacts violently
    with gallium perchlorate.
    Benural 70 B-I-K
    Carbamide Carbamimidic acid
    Carbonyl diamide Isourea
    Nimin Pseudourea
    UR Urea perhydrate
    Ureaphil Ureophil
    Urepearl Urevert
    Varioform II
    .
    Overall Evaluation
    IRPTC Data Profile
    Identifiers,Physical and Chemical properties 2
    Although urea has generally low ecotoxicity to organisms,its well documented indirect and longterm effects to
    the ecosystems,e.g.eutrophication,groundwater pollution,soil acidification and ammonia emissions to air
    should be considered.
    Urea is an important endogenous product of mammalian metabolism.This may partly explain why it has not
    been rigorously studied with toxicological tests.Nevertheless,urea appears to cause little or no toxicity to most
    mammalian species (ruminants are an exception)and humans at reasonable dose levels.The tentatively
    determined EHE is lower than the EDLC based on human observations.
    .)
    ENVIRONMENTAL EXPOSURE
    Urea is "ultimately biodegradable".
    Degradation
    Urea is ultimately biodegradable in inherent biodegradability test (OECD 302 B).In semi-continuous activated
    sludge (SCAS)urea is biodegraded on the average of 93-98%in 24-hour cycle.
    The main mode of degradation is enzymatic mineralization.In soil and water urea is expected to biodegrade
    fairly rapidly to ammonia and bicarbonate if temperature is not too low.Ammonia is a volatile gas in alkaline
    solutions.In natural waters,most ammonia appear in the form of ammonium,from which nitrogen is oxidized
    IRPTC Data Profile
    Identifiers,Physical and Chemical properties 3
    as the result of bacterial action,forming nitrite and nitrate.
    According to US-EPA PCGEMS-model hydrolysis of urea is expected to be extremely slow (T1/2 >1 years).
    Bioaccumulation:
    Due to low log Pow value (-1.59 at 20-25 C)urea is not likely to undergo bioaccumulation.
    DISTRIBUTION BETWEEN ENVIRONMENTAL COMPARTMENTS AND OCCURENCE IN THE ENVIRONMENT
    The model used for estimating the partitioning of urea in the environment was the Mackay level 1 model.
    According to the model there is 99.84%and 0.16%partitioning into water and air,respectively.
    (i)Air
    Urea is essentially non-volatile in solid form.Its high water solubility,low vapour pressure (solid pure urea 80 Pa
    at 20C;calculated)and consequently low Henry's law constant (4.4E-8 atm m3/mol)indicate that urea will not
    evaporate from water to atmosphere.
    Degradation of urea to ammonia causes NH3-emissions to air.Emissions are higher in alkaline soil (pH>7).
    (ii)Soil
    According to the worldwide use pattern of urea,when 85 -90%of urea is used as a fertilizer,the highest
    environmental exposure is to soil.Urea is,however,relatively leachable from the soil into the surface and the
    groundwater because of its weak adsorption to the soil,high water solubility and low soil-water partition
    coefficient.This can happen especially if the soil surface is saturated with water,as might be the case after a
    rainfall.
    (iii)Water
    As earlier described,urea can be leached relatively easily into the surface water and the groundwater.The
    concentration of urea itself,however,is not generally detected,because of its high degradation rate.Therefore
    usually degradation products e.g.nitrate,nitrite and ammonium can be measured.
    Some monitoring data are,however,available:
    a)the concentration of urea in domestic sewage:2 -6 mg/L and in primary sewage plant effluent:0.016 -0.043
    mg/L.
    b)the concentration of urea in sewage of Kemira's fertilizer factory (Finland):0.34 mg/L.
    The monitoring data has been further used for calculation of the predicted environmental concentration (PEC).
    For calculation of PEC the dilution factors of 10 for domestic waste water effluents and 100 for industrial
    effluents are used.Thereby (a)PEC of 0.0016 -0.0043 mg/L is obtained for primary sewage plant effluent and
    (b)PEC of 0.0034 mg/L for fertilizer factory.
    Environmental exposure by consumer use can be considered insignificant.


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  5. [5]
    أبوبكرمصطفى
    أبوبكرمصطفى غير متواجد حالياً
    عضو فعال


    تاريخ التسجيل: May 2006
    المشاركات: 92
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    طلب معلومة يا أخوان

    الأخ الكريم الكيميائي الحر
    ألف شكر علي جهدك المقدر وسرعة تفاعلك معي , لكن أخي الفاضل لم أجد المعلومات التى طلبتها حتي الان , أرجو المساعدة ما أمكن ذلك.
    مع وافر الشكر.

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  6. [6]
    م ب
    م ب غير متواجد حالياً
    عضو فعال جداً


    تاريخ التسجيل: Jul 2006
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    السلام عليكم
    ممكن من المعلومات السابقه تستنتج الي بدك ياه و ين الهندسه يا أخ أبو بكر؟

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