Chemistry

What would be the effect of each of the following on the calculated molecular weight of the solute?

a) some cyclohexane evaporated while the freezing point of pure cyclohexane was being measured. ( i think it would be higher)

b)Some cyclohexane evaporated after the solute was added. ( i think it would be lower)

c) a foreign solute was already present in the cyclohexane. (i think it would have no change)

d) the thermometer is not calibrated correctly. it give a temp that is 1.5 C too low at all temperatures. (i think it would be higher)

  1. 👍
  2. 👎
  3. 👁
  1. Can not be positive, but switch your answers for c and d, and your answer for a should say lower.

    1. 👍
    2. 👎
  2. I'm going to differ with both of you.Here are the formulas used to solve for molecular weight.
    (1)...delta T = Kf*m
    (2)...m = mols/kg solvent
    (3)...mol weight = grams/mols

    a. no effect. The normal freezing point of pure cyclohexane will be same whether you determine the freezing point on 1 mL or on 100 mL.

    b. I think lower is right. Why? If some of the solvent evaporated after adding the solute, then m is higher from 2) which makes mols higher. mols higher in 3) makes molecular weight smaller.

    c. I think c is right at no change. The foreign material is constant and the effects are constant so delta T will be the same (although T initial and T final may not be the same).

    d. no change. So the thermometer reads 1.5 too low every time it's read. T final and T initial readings will not be right BUT the difference (delta T) will always be the same and that's all you're using in the calculations.

    1. 👍
    2. 👎
  3. Didn't even think to look at it that way.

    1. 👍
    2. 👎
  4. Actually, it is not pure cyclohexane, cyclohexane is the solvent in the solution.That should have been specified to get an accurate response.

    1. 👍
    2. 👎

Respond to this Question

First Name

Your Response

Similar Questions

  1. A.P Chemistry

    Three volatile compounds X,Y, and Z each contain elements Q. The precent by weight of element Q in each compound was determined. Some of the data obtained are given below Percent by weight Molecular Compound of Element Q Weight X

  2. Chemistry

    1. What happens if our calorimeter is not properly insulated..what effect will it have on our calculated specific heat capacity I.e too large, too small or no effect....explain. 2. If our partner forgot to cover the coffee cup

  3. AP CHEMISTRY HELP

    a) A student fails to wash the weighing paper when transferring the KHP sample into the beaker. What effect does this error have on the calculated molarity of the NAOH solution? Mathematically justify your answer. b) A student

  4. Chemistry

    A student performed an experiment to determine the molecular weight of a gaseous compound. Using the ideal gas law PV = nRT, and knowing the pressure, temperature, and volume of the vapor, the student calculated the number of

  1. chemistry

    suppose the hydrate was heated too quickly and some of it was lost as it spattered out of the container . explain how this would effect . a. the calculated mass of water in the compound b. the molecular formula you determined.

  2. Chemistry

    Find the molecular formula of a compound that is 48.38% carbon, 8.12% hydrogen, and 53.5% oxygen by mass and has a molecular weight of 328 g/mol.

  3. Chemistry

    A quantitative amino acid analysis reveals that bovine serum albumin (BSA) contains 0.58% tryptophan (Mr 204) by weight. A) Calculate the minimum molecular weight of BSA (i.e. assume there is only one Trp residue per protein

  4. physical chemistry

    The system N2O4 2NO2 maintained in a closed vessel at 60ยบ C & a pressure of 5 atm has an average (i.e. observed) molecular weight of 69, calculate Kp. At what pressure at the same temperature would the observed molecular weight

  1. Chemistry

    An ideal gas differs from a real gas in that the molecules of an ideal gas: have no kinetic energy have a molecular weight of zero have no attraction for one another have appreciable molecular volumes have an average molecular

  2. Stoichiometry Test

    3.Empirical formula is C4H5N2O.Its molecular weight is 194.19g/mole.The "empirical formula weight is about 97.1g/mole.What is the molecular formula ?

  3. chemistry

    Molecular Mass by Freezing point Depression (Preliminary Lab) The following errors occurred when the above experiment was carried out. How would each affect the calculated molecular mass of the solute (too high,too low, no

  4. One more A.P Chemistry

    Three volatile compounds X,Y, and Z each contain elements Q. The precent by weight of element Q in each compound was determined. Some of the data obtained are given below Percent by weight Molecular Compound of Element Q Weight X

You can view more similar questions or ask a new question.