A solution is prepared by dissolving 20.2 {\rm mL} of methanol ({\rm{CH}}_3 {\rm{OH}}) in 100.0 {\rm mL} of water at 25 ^\circ {\rm C}. The final volume of the solution is 118 {\rm mL}. The densities of methanol and water at this temperature are 0.782 {\rm g/mL} and 1.00 {\rm g/mL}, respectively. For this solution, calculate each of the following.
find 1 ) molality
2) percent by mass
3) moles fraction
4 )mole fraction
5) molarity

  1. 👍
  2. 👎
  3. 👁
  1. 20.2 mL CH3OH + 100 mL H2O. Final volume = 118 mL.
    Use density to convert 20.2 mL CH3OH to grams. mass = volume*density = 20.2*0.782 = about 15 g(but you need to do it more accurately than that).
    Convert 15g to mols. mol = g/molar mass = 15/32 = about 0.5 mol.
    Then molality = mols/kg solvent = 0.5/0.1 = ?

    2)percent w/w = (grams solute/g soln)*100.
    mass solute = about 15g
    mass solvent = 100 g
    mass solution = 100 + 15 = 115 g
    %w/w = (15/115)*100 = ?

    mole fraction CH3OH = XCH3OH = mols CH3OH from #1/total mols.
    XH2O = mols H2O/total mols.
    mols H2O = grams/molar mass = 100/molar mass.

    4. Same as 3?
    5.M = mols/L soln. You know mols from #1, L soln = 118 mL = 0.118 L.

    NOTE: I assume you are same poster under various screen names of aa, anonymous, and others who insist on making this difficult for you to type and for us to answer by continuing to use symbols that, in my opinion, have no place in the question or the subject. 20.2 mL is 20.2 mL no matter how you slice it; writing it as 20.2{\rm
    mL} is not only confusing but, in my opinion, is gibberish. You could save yourself a lot of typing time and you could make it lot easier for us to understand and respond by keeping this rubbish out of your posts.

    1. 👍
    2. 👎

Respond to this Question

First Name

Your Response

Similar Questions


    A solution of a metal carbonate M2CO3, was prepared by dissolving 7.46 g of the anhydrous solid in water to give 1000cm^3 of solution. 25.0cm^3 of this solution reacted with 27.0cm^3 of 0.100 mol/dm^3 hydrochloric acid. Calculate

  2. Chemistry

    A solution is prepared by dissolving 23.7 g of CaCl2 in 375 g of water. The density of the resulting solution is 1.05 g/mL. The concentration of Cl- in this solution is __________ M. can someone help me? how do i get to M?

  3. Chemistry

    The density of acetonitrile (CH3CN) is 0.786g /mL and the density of methanol (CH3OH) is 0.791g/mL. A solution is made by dissolving 22.5 mL of CH3OH in 98.7 mL of CH3CN . (a) What is the mole fraction of methanol in the solution?

  4. quant chemistry

    A standard solution of Mn2+ was prepared by dissolving 0.250 g of Mn in 10 mL of concentrated HNO3 (measured with a graduated cylinder). The resulting solution was quantitatively transferred to a 100 mL volumetric flask and

  1. General Chemistry

    A solution was prepared by dissolving 18.00 grams glucose in 150.0 grams water. The resulting solution was found to have a boiling point of 100.34 0C. Calculate the molar mass of glucose. (Kb (water) = 0.51 0C kg/mol; Tb(water) =

  2. AP Chemistry

    The normal boiling point of methanol is 64.7°C. A solution containing a nonvolatile solute dissolved in methanol has a vapor pressure of 642.3 torr at 64.7°C. What is the mole fraction of methanol in this solution?

  3. chemistry! URGENT

    A standard solution is prepared for the analysis of fluoxymesterone (C20H29FO3), an anabolic steroid. A stock solution is first prepared by dissolving 10.0 mg of fluoxymestrone in enough water to give a total volume of 500.0 ml. A

  4. chemistry

    the vapor pressure of ethanol at 20c is 44 mmHg and the vapor pressure of methanol at the same temperature is 94mmHg. A mixture of 30.0 g of methanol and 45.0 g of ethanol is prepared (and can be assumed to behave as an ideal

  1. Science

    A solution has been prepared by dissolving 0.63 g of HNO3 in 100 ml.What is its pH value ?

  2. Chemistry

    Calculate the pH of a solution prepared by dissolving 12.2 g of benzoic acid in enough water to produce a 500 mL solution. Ka = 6.3 x 10^-5

  3. chemistry

    A solution is prepared by dissolving 0.5842g of oxalic acid (H2C2O4) in enough water to make 100.0ml of solution. A 10.00ml aliquot (portion) of this solution is then diluted to a final volume of 250.0ml. What is the final

  4. Chemistry

    A solution is prepared by dissolving 130 g of NaNO3 in 100 g of water at 80°C. The solution is cooled to 0°C. How many grams of compound remain in solution? How many grams of solid are formed?

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