Determination of molar mass by freezing point depression page 3 of 6 drawing the straight line in the solid-liquid region of the graph, ig nore points where supercooling is observed. Using freezing-point depression to find molecular weight lab report abstract: in this lab, we used freezing point depression to find the molar mass of biphenyl this was done by transferring cyclohexane from a liquid to solid state and then melting it from a solid back to a liquid. Computer 4 advanced chemistry with vernier ©vernier software & technology 4 - 1 using freezing-point depression to find molecular weight when a solute is dissolved in a solvent, the freezing temperature is lowered in proportion to the. Determination of molecular mass by freezing point depression page 3 of 10 the cooling behavior of a solution is somewhat different from that of a pure liquid (see figure 2) the temperature at which a solution freezes is lower than that for the pure solvent. The molal freezing point depression constant for h2o, kf , is given as measured decrease of freezing point, ∆tf, to calculate the molar mass of an unknown nonvolatile nondissociating solute report sheet safety: 1) caution: the unknown sample is toxic make sure to handle it carefully without spilling.
• find the molar mass of a solute by the method of freezing-point depression • evaluate the accuracy of the method by comparison to a molar mass calculated from a molecular formula. 1 the k f value for lauric acid is 39°c•kg/mol use the freezing point depression equation to determine the molality, m, of the lauric acid in the test tube containing the mixture. Measuring the freezing point depression, dt, and the mass of benzoic acid, you can use the formula above to find the molecular weight of the benzoic acid solute, in g/mole.
1 chemistry 101 15-molecular weight by freezing point depression investigations into the nature of solutions have shown that certain properties are different for the solution compared to the pure solvent. Middle east technical university opencourseware [ ] chemistry department 8 molecular weight determination from freezing point depress. Determination of the molar mass of a compound by freezing point depression since the molar mass m (traditionally and often, but erroneously called the molecular weight) of a compound has units g/mole, we can solve for moles and substitute the result into the molal report: in your lab report briefly discuss the theory behind why the. Using freezing point depression to find molecular weight advanced chemistry with vernier 4 - 3 12 obtain a test tube containing a melted solution with ~1 g of benzoic acid dissolved in ~ 8 g of. Using freezing-point depression to find molecular weight abstract: in this lab, the purpose was to use the freezing point depression method to determine the molecular weight of aspirin this was done by determining the freezing of t-butanol and that of a t-butanol and aspirin solution then finding the molality of the solution, and moles of.
Molecular mass by freezing point depression prelab purpose graphs conclusion 1 to determine the molecular mass of an unknown substance by finding the freezing point of two solutions (bht and para-dichlorobenzene, and bht and the unknown. Ap lab report 2: freezing point depression lance schell, colin livasy, erin tatman, and niral rajyaguru park hill south high school block one advanced placement (ap) chemistry january 20, 2009 abstract in this lab, the purpose was to use the freezing point depression method to determine the molecular weight of benzoic acid. Chm130 colligative properties experiment: determination of molar mass by freezing point depression using paradichlorobenzene introduction: the vapor pressure of a pure liquid at a given temperature is a characteristic property of that liquid however, when a nonvolatile solute is dissolved in the liquid, the vapor.
Q1: calculate and enter the freezing point depression of a solution of 802 g ethylene glycol (c2h6o2) in 832 g h2o k(subscript)f for h2o is 186 °c kg/mol q2: a solution which contains 603 g of an unknown molecular compound in 352 g of water freezes at -562°c. Using freezing-point depression to find molecular weight formal lab report purpose: the purpose of this lab is to be able to use the freezing point of a substance to find the molecular weight of it to do this, we will use the logger pro program to obtain the freezing point of lauric acid and a solution of benzoic acid and. Molecular weight by freezing point depression mr keefer introduction the melting point is the temperature at which the crystal structure of a solid breaks down with increasing entropy (+δs.
In this lab, the purpose was to use the freezing point depression method to determine the molecular weight of aspirin this was done by determining the freezing of t-butanol and that of a t-butanol and aspirin solution then finding the molality of the solution, and moles of aspirin. Molecular mass by freezing point depression lab fp1 juniata college science outreach new and improved introductory manual, 2000 introduction once a solution has been formed, the solution displays properties different from those of. The colligative properties include vapor pressure lowering, boiling point elevation, freezing point depression, and osmotic pressure the vapor pressure is the escaping tendency of solvent molecules the vapor pressure is the escaping tendency of solvent molecules. By measuring the freezing point depression, ∆t, and the mass of benzoic acid, you can use the formula above to find the molecular weight of the benzoic acid solute, in g/mol.
Molar mass is useful to identifying an unknown substance methods such as using finding the freezing point depression of an unknown substance can help in finding the identity in this laboratory, we will find the molar mass of an unknown substance that was combined with bht using freezing point depression. The freezing point of a solution that contains 100 g of an unknown compound, (a), dissolved in 100 g of benzene is found to be 207 o c the freezing point of pure benzene is 548 o c the molal freezing point depression constant of benzene is 512 o c/molal. Using freezing-point depression to find molecular weight annotation freezing-point depression, a colligative property, is investigated technology is used to collect. A calculate molality (m), in mol/kg, using the formula the kf value for lauric acid is 39°c•kg/mol b calculate moles of benzoic acid solute, using the molality and the mass (in kg) of lauric acid solvent.