Chemistry

The freezing point of ethanol is -114.6 C and its Kf value is 2.00 C/m. What is the freezing point for the solution prepared by dissolving 50.0 g of glycerin (C3H8O3) in 200.0 g ethanol?

I used Change in temp=Kfm
kf=2.00
I calculated m to be 2.1736.
I ended up the answer of -118.4 C but the answer is apparently -120. I'm a few numbers off, can someone explain to me where I went wrong?

  1. 👍
  2. 👎
  3. 👁
  1. mols glycerin = grams/molar mass = 50/92 = about 0.54 but you can clean that up (as well as the numbers following also).

    m = mols/kg solvent
    m = 0.54/0.200 = about 2.7

    dT = Kf*m = 2.00*2.7 = about 5.4.

    New freezing point = -114.6-5.4 = about 120.

    1. 👍
    2. 👎

Respond to this Question

First Name

Your Response

Similar Questions

  1. Chemistry

    The boiling point of an aqueous solution is 102.48 °C. What is the freezing point? I know that formula for freezing point is delta Tf = Kf*m but what do I plug in for each?

  2. Chemistry

    Calculate the freezing point of a solution of 3.46 g of a compound,X,in 160 g of benzene. When separate sample of X was vaporised, its density was found 3.27 g/L at 116 c and 773 torr. The freezing point of pure benzen is 5.45 c,

  3. Chemistry

    Explain why the freezing point of a pure solvent is constant, whereas the freezing point of a solution decreases with steady cooling.

  4. chemistry

    Assuming equal concentrations, rank these aqueous solutions by their freezing point.? K2CO3, Li3PO4, Sn(ClO3)4, NH4I I tried to rank them according to the number of ions but i can't get it. highest freezing point --> lowest

  1. Chemistry hw

    Assuming 100% dissociation, calculate the freezing point and boiling point of 3.13 m SnCl4(aq). Tf=? Tb=? My work: SnCl4 with 100% dissociation gives a van't hoff factor of 5, 1Sn 4+ ion and 4 Cl- ions deltaT = i x Kf x m for

  2. Chemistry

    How many grams of ethanol must be added to 500.0 g of water to make a solution that freezes at 0.00 degrees fahrenheit? The molal freezing point depression constant for water is 1.86 degree celsius over moles.

  3. I am so lost

    The freezing point of pure cyclohexane is 6.60°C and the freezing point depression constant is 20.00°C/m. The freezing point of a solution containing 0.161 g of an unknown nonelectrolyte solute and 5.818 g of cyclohexane was

  4. Chemistry

    Ethanol (C2H5OH) melts at -114 degrees Celsius. The enthalpy of fusion is 5.02 kj/mol. The specific heats of solid and liquid ethanol are 0.97 J/g-K, respectively. How much heat (kJ) is needed to convert 25.0 g of solid ethanol at

  1. chemistry

    Ethanol (C2H5OH) melts at -114 °C. The enthalpy of fusion is 5.02 kJ/mol. The specific heats of solid and liquid ethanol are 0.97 J/g-K and 2.3 J/g-K, respectively. How much heat (kJ) is needed to convert 25.0 g of solid ethanol

  2. chem

    The "proof" of an alcoholic beverage is twice the volume percent of ethanol, C2H5OH, in water. The density of ethanol is 0.789g/mL and that of water is 1.99g/mL. A bottle of 100-proof rum is left outside on a cold winter day. a)

  3. CHEMISTRY

    Assuming equal concentrations, rank these aqueous solutions by their freezing point: LiSO4, Li3PO4, SnCl4, NH4Br. (from highest freezing point to lowest freezing poinT) Thanks.

  4. science

    Suppose that the amount of heat removed when 42.1 kg of water freezes at 0.0 °C were removed from ethyl alcohol at its freezing/melting point of −114.4 °C. How many kilograms of ethyl alcohol would freeze?

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