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Chemistry problems (help please)

  1. Nov 24, 2006 #1
    I have a few questions, that I hope you guys will be able to help with.

    1. Suppose you have two metals, A and B, and the solutions of their ions, A+ and B+, Metal B is more active than metal A.
    Write the spontaneous redox reaction for this situation.
    (I know redox reactions are reactions in which metals oxidize and reduce, but what does this question want to know?)

    2.) Which of the following are redox reactions?
    a.) 2Na + 2H2O ---> 2NaOH + H2

    b.) SO2 + H2O ---> H2SO4

    3.) Why are liquids and solids referred to as condensed phases?
    The only thing I can think of for this is that their atoms/molecules are closer together than gas, which are far apart.

    4.) Describe each phase of matter on the molecular level with respect to the amount of order and energy present.

    What exactly is this question asking??

    5.) All of the following are solids at room temperature. Classify them as molecular, ionic, network, or metallic.
    a.) potassium, melting point = 64*C
    b.) red phosphorus, mp = 590*C
    c.) Boron triiodide, mp = 50*C
    My guesses:
    A.) Metallic
    B.) Molecular
    C.) Boron Triiodide
    (Can anyone confirm or direct me?)


    6.) Describe each phase of matter on the molecular level with respect to the amount of ENERGY present. (Just energy this time, not order).
    What exactly is this question asking?



    Can anyone tell me how I can tell, or what I need to do, in order to know what they're classifed as.

    Thanks for all the help guys. If you don't necessarily want to give me the answers, that is fine, but please lead me in the right direct or provide a source of some sort. Unfortunately for me, most of these questions don't have explicit answers in the book. Like for example, in answer to #5, the book defines ionic molecular solids as solids "represented by sucrose". Not a very good definition if you ask me....

    Thanks for all the help in advance!
     
  2. jcsd
  3. Nov 25, 2006 #2
    2.) Which of the following are redox reactions?
    a.) 2Na + 2H2O ---> 2NaOH + H2

    I can't really explain what they are better than your book or teacher. But, I know that working and seeing examples can help a lot. Check out a)

    2Na+ + H2 + 2OH- = 2Na + 2H2O

    Do the questions over and over in the back of your book and those will become really easy.

    3) Liquid and solid molicules are still under the influence of one another. Hydrogen bonding, for example, makes 2 molecules bind tightly together. But when the two molecules become energized to the point that they leave one another's presence, the force between them becomes nothing as their distance increases. As for "condensed," the only fluids that are able to be condensed are gasses, because as I said earlier they are not being repulsed by that extremely strong force which keeps the nuclei of any two atoms from getting close. You will see a chart that looks like a tipped over letter "Y", and it will represent pressure versus heat for the various phases of materials. If you check it out, you will see that there is not enough pressure nor a cold enough lab to push a solid into a more condensed phase. These situations do occur under extreme conditions, but we leave that to the astrophyicisists to worry about.

    4) Molecules have several reasons for wanting to stay near one another. If you recall, there are polar molecules that are attracted to one another's opposite charges. There is also Hydrogen bonding, van der waals (or something like that) forces...among others. The only thing that can make these molecules leave eachother is if someone gives them energy to do so. It's like hanging out with your buddies...you don't wanna leave unless you get a serious burst of energy. Here is the order:

    Solids:
    They have the advantage of relatively high atmospheric pressure pushing themselves together, along with a lack of thermal energy. The more reasons for the solids to stick (hydro bonds, waan der walls...polar attraction), the more energy it will take for them to leave eachother. If the pressure lets down just a little, or someone turns up the heat then:

    Liquids:
    Still wanting to hang out with one another, but they are willing to go from one friend to the next. The molecules have just enough energy to move around eachother, but not enough energy to actually leave. If the heat goes way up, or the spaceship door opens and the pressure drops to zero then,

    Gasses:
    They have so much kinetic and thermal energy and so little atmospheric pressure that they do not encounter themselves enough for their attractive forces to bind them together. You can see this yourself when you shower tomorrow. You are going to get shower water molecules so hot that they break their hydrogen bond attractions and go flying around your bathroom. The minute they bump into your cold mirror though, their thermal energy will diffuse from the hot molecule into the cold mirror, and those molecules will wind up 'condensing' into a liquid.

    5.) All of the following are solids at room temperature. Classify them as molecular, ionic, network, or metallic.

    a.) potassium, melting point = 64*C

    Room Temp is ~24 degrees, so this one is gunna be solid. I gotta eat, I'll follow up soon
     
  4. Nov 27, 2006 #3
    Thanks for your help, I've done the rest. You really explained number 4 really well.
     
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