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Homework Help: Some Chem Q's

  1. May 15, 2005 #1
    Hey guys, i just have some quick questions i'm having trouble with. I'm in a hurry right now so i'll come back tommorow and type up what I was thinking about them, here are the questions.

    1) Farmers use ferilizers mainly to replace depleted nutrients in the soil. Liquid ammnia and ammonium nitrate are two substances that are used to replace essential nitrogen in the soul. Based on the percentage of nitrogen by mass, which of these two chemicals would be the better fertilizer? Assume that the cost per kilogram of each chemical is about the same.

    2)a) How many grams of sulphuric acid will neutralize 10.0 g of sodium hydroxide?

    b) What volume of water vapour at 100C and 110 kPa would also be produced?

    3) An industrial plant that specializes in cleaning up waste liquids is confronted with a problem of separating the metal ions found in the large vat of solution. By analysis, the solution was found to contain varying quantities of silver, barium, and iron(III) ions. Suggest a procedure for separating the metal ions by precipitation.

    Thanks in advance for anyone that is willing to help.
  2. jcsd
  3. May 16, 2005 #2
    Sorry, but we don't do your homework for you.

    How far have you gotten with it so far, then we can let you know what to do next.
  4. May 16, 2005 #3
    This isent homework, i'm learning chemistry on my own, and i'm not asking you to do it for me, i'm asking someone to point me in the right direction.

    For number 2a, i'm pretty sure this is a mass-mass problem, but im not sure, can someone confirm?..and for b, i dont understand that problem.\

    for 1) i was thinking if i should find the formula for liquid ammonia and ammonium nitrate, and then finding which one has more nitrigoen by mass, and whichever has more would be the better fertlizer, but again, im not sure.

    for 3) i am completely lost and have no idea what to do.

    thanks in advance again
  5. May 16, 2005 #4


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    Find out which has a greater fraction of nitrogen. Understand why the "fraction" is what matters.

    What do you mean by this ? Show your working, and we'll tell you if it's wrong. How do you start off on a problem like this ?

    If you have no idea about "qualitative analysis" there's little we can do to help here. Read up the relevant chapter in your text or Google it.
  6. May 16, 2005 #5
    Find the RFM (relative formula mass) for the two compounds, and then divide the RAM (relative atomic mass of nitrogen) by the RFM of each compound and multiply by 100 to give the percentage by mass.

    All these are equation based qs, i'm sure if you google in chemistry volumetric analysis, or molarity equations, or titration you will find them. If you can't just ask and I'll send my working.


  7. May 19, 2005 #6
    Gokul, i dont understand what you mean by fraction.

    Ben, i did what you said, and i got....

    Liquid Ammonia = NH3 = 14/17 = .82 *100% = 82%
    Ammonium Nitrate = NH4NH3 = 14/35 = .40 *100% = 40%

    So since the liquid ammonia has a higher percentage of nitrogen, then it is the better fertilizer...is this correct?

    I figured out number 2a and b, thanks for the help anyway.

    BUT, i still have no idea what to do with 3, does it have to do with net ionic equations?

    I also have some more questions i'm having problems with..

    1) Write equations for the neutralization reactions that result in the formation of the following salts:

    a) lithium carbonate -- i put -- H2CO3 + LiOH --> Li2CO3 + H20
    b) copper(II)chlorate --i put -- HClO3 + CUOH ---> Cu(ClO3)2 + H20
    c) aluminium sulphate -- i put -- H2SO4 + Al(OH)3 --> Al2(SO4)3 + H2O
    d) ammonium iodide -- i'm stuck on this one, the formula for this is NH4I, this base is NH4OH but what is the acid? and also do i have to balance these as well?

    2) Fir each of the follwing situations, identify those for which a reaction is likely to occur. For those that do occur, write a net ionic equation.

    a) chromium dipped into silver nitrate
    b) gold immersed in hydrochloric acid
    c) nickel pellets dropped into calcuium acetate
    d) aluminium dropped into a bath of sulphuric acid
    e) zinc dipped into a solution of lead(II)nitrate

    I'm not sure what to do here, does it have to do with electronegativites?

    3) A chemist wishes to prepate 200 mL of a saturated solution of BaF2, the concentration of which is 6.3 * 10^-3 mol/L. Determine the mass of BaF2 tat will be needed to make up the 200 Ml of the solution.

    do i have to use this formula C= n/v, is there another formula i have to use for this?

    Thanks again for the people that help
    Last edited: May 19, 2005
  8. May 20, 2005 #7

  9. May 21, 2005 #8

    here's what i see, you want to make 1/5th of a litre of .0063 M soultion, using X grams of BaF2, so first you find how many Moles of BaF2 there will be in the solution, and multiply the value you get by the gram molecualr weight of BaF2,

    does that let you understand the problem?

    EDIT: i said too much, so i took out the actual solution
    Last edited: May 22, 2005
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