Chemistry

posted by .

Analysis of a compound indicates that it is 49.02% carbon, 2.743% hydrogen, and 48.23% chlorine by mass. A solution is prepared by dissolving 3.150 grams of the compound in 25.00 grams of benzene, C6H6. Benzene has a normal freezing point of 5.50degreeC and the solution freezes at 1.12degreeC. The molal freezing point constant,kf, for benzene is 5.12C/molal.
1.Find the empirical formula of this compound.
2.Using the freezing point data calculate the molar mass of the compound.
3. Calculate the mole fraction of benzene in the solution.
4. The vapor pressure of benzene at 35degreeC is 150.0mmHg. Calculate the vapor pressure of benzene over the solution described in this problem at 35degreeC.

  • Chemistry -

    Part 1.
    Take a 100 g sample. That will give you
    49.02 g C, 2.743 g H, and 48.23 g Cl.
    Convert grams to moles.
    49.02/12.01 = ??
    2.743/1.008 = ??
    48.23/35.45 = ??
    Find the mole ratio of the elements to each other. The easy way to do this is to divide the smallest number by itself (thus assuring that will be 1.00), then divide the other two numbers by the same small number. Round to whole numbers. That will give you the empirical formula.

    part 2.
    delta T = Kf*molality
    solve for molality.
    m = moles/kg solvent.
    Solve for moles.
    moles = grams/molar mass
    solve for molar mass.

    part 3.
    mole fraction benzene = moles benzene/total moles. You have grams benzene which can be convert to moles and you have moles of the unknown compound.

    part 4.
    Pbenzene = Xbenzene*Pnormal benzene.
    post your work if you get stuck.

  • Chemistry -

    1) C=3 ;H=2 and Cl=1
    so the empirical formula of the compound is C3H2Cl.

    I seem not to get the others clear.

  • Chemistry -

    C=3 ;H=2 and Cl=1. Therefore the empirical formula of the compound is C3H2Cl

    The others don't seem clear to me

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. Chemistry

    The molar mass of a non-dissociated, non-volatile compound is to be determined by dissolving 5.00 g of the compound into 50.0 g of benzene. The freezing point of benzene was lowered by 2.5 degrees C. The freezing point depression constant …
  2. chem- molar weight

    I worked this problem, I would like to know if I did it correctly, I think I missed something, I'm not sure..... When a 20.0 gram sample of an unknown compound is dissolved in 500 grams of benzene, the freezing pointof the resulting …
  3. chem

    a compound containing only boron, nitrogen and hydrogen was found to be 40.3% B, 52.2%N, and 7.5% H by mass. If 3.301g of this compound is dissolved in 50.00g of benzene, the solution produced freezes at 1.30 degrees celsius. If Kf(freezing …
  4. Chemistry

    Pure benzene has a normal freezing point of 5.50 degrees Celsius. A solution containing 11.4 grams of a molecular substance dissolved in 150.0 grams of benzene (Kf=5.12C/m) has a freezing point of 1.20 degrees Celsius. What is the …
  5. Chemistry

    Analysis of a compound indicates that it is 49.02% carbon, 2.743% hydrogen, and 48.23% chlorine by mass. A solution is prepared by dissolving 3.150 grams of the compound in 25.00 grams of benzene, C6H6. Benzene has a normal freezing …
  6. Chemistry

    Analysis of a compound indicates that it is 49.02% carbon, 2.743% hydrogen, and 48.23% chlorine by mass. A solution is prepared by dissolving 3.150 grams of the compound in 25.00 grams of benzene, C6H6. Benzene has a normal freezing …
  7. Chemistry

    Benzene (C6H6) is an organic compound that boils at 80.1°C. If 100.0 grams of liquid benzene at 18.5°C is given 16.88 kJ of energy, what is the final temperature (in °C) of the benzene?
  8. chemistry

    the freezing point of benzene C6H6 is 5.5000C at 1 atmosphere. In a laboratory experiment, students synthesized a new compound and found that when 10.70 grams of the compound were dissolved in 294.0 grams of benzene, the solution began …
  9. Chemistry

    What will be the freezing point of a solution made by dissolving 5.25 g of naphthalene (C10H8) in 100.0 g benzene (C6H6?
  10. Chemistry

    An unknown compound contains only carbon, hydrogen, and oxygen. Combustion analysis of the compound gives mass percents of 31.57% Carbon and 5.30% H. The molar mass is determined by measuring the freezing-point depression of an aqueous …

More Similar Questions