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chemistry - amount concentration of solution problem

  • 03-11-2013 5:10pm
    #1
    ChromosomeT
    Registered Users, Registered Users 2 Posts: 80 ✭✭


    how would i work out an equation like this? i'm a bit confused..Calculate the amount concentration of a solution containing 0.25 mol of NiCl2 in 500 mL of solution


Comments

  • #2
    Gru
    Registered Users, Registered Users 2 Posts: 1,156 ✭✭✭Gru


    Nickel has an atomic weight of 58.6934 and Chlorine has an atomic weight of 35.45, so NiCl2 would have a total atomic weight of 129.5934. So 1 mol of this would be 129.5934 g/L, 0.25 of this would be 32.39835 g/L, so I think from the way you've it written there it would be 32.39835 g in 500ml of solution which would be the same as 0.5mol/L so your final concentration should be 0.5mol/L.


  • #3
    ChromosomeT
    Registered Users, Registered Users 2 Posts: 80 ✭✭ChromosomeT


    http://s784.photobucket.com/user/tk_tomas/media/Mobile%20Uploads/image_zpsc48a29f1.jpg.html

    i'm wondering if someone could have a look at this problem sheet i'm having a bit of difficulty with in a few questions. I can do questions 1-4 ok but from 5 onwards even with referring to my notes i'm stugling a bit. I'd be grateful if anyone could help set me on the right path to solve these problems


  • #4
    SOL
    Registered Users, Registered Users 2 Posts: 1,155 ✭✭✭SOL


    Concentration is measure in moles per liter - that is just a description of how many moles of whatever you are measuring would be in 1 liter of that solution.

    If you know the number of moles in 1 liter, you can multiply that by however many liters you have and that will tell you the total number of moles you have.

    If you want to answer 4, just multiple the volume in litres (0.0243L) by the molarity X mol/L and you get the number of moles (Litres in will cancel because L/L = 1)

    Now if you look back to your equation, you said some number of H2SO4 molecules react with every CaCO3 molecules when you balanced the equation.

    So you know for every CaCO3 there are x number of H2SO4s.


    Using this just multiply the number of CaCO3 molecules you found there to be (counted in moles for convenience) and you will know how many H2SO4 molecules there were.

    If you know how many moles of h2so4 there were in a given volume you can calculate out concentration - moles divided by the volume in litres will give you moles/L or M.

    You also balanced the equation to find out how many CO2 would be produced per CaCO3 so use that to find out how many moles of CO2 there are and multiply it by the volume given.


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