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NCSU CH 202 - Lab 03 Prelab

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1. 6/6 points Last Response | Show Details All Responses Notes This item deals with safety issues in the Freezing Point Depression experiment. Choose the answer that best completes each statement. a. Stearic and lauric acids are nonhazardous but prolonged contact with skin may cause irritation . b. If either compound is spilled on the skin, it should be washed with soap and water .2. 2/2 points Last Response | Show Details All Responses Notes This item deals with waste disposal in the Freezing Point Depression experiment.Choose the answer that best completes this statement. All wastes should be placed in the labeled waste container .3. 3/3 points Last Response | Show Details All Responses Notes The following questions all apply to the experiment "Freezing Point Depression."a. Which of the following is not a colligative property? (_) freezing point depression (o) density enhancement (_) osmotic pressure (_) vapor pressure lowering (_) boiling point elevation b. What common colligative property will you be exploring? (_) boiling point elevation (o) freezing point depression (_) density enhancement (_) osmotic pressure (_) orbital expansion (_) vapor pressure lowering (_) solution contraction c. Which of the following statements is NOT true? (_) The van't Hoff factor for K3PO4 is 4 (_) The van't Hoff factor for lauric acid is 1 (_) Molality includes the moles of solute and the mass of solvent (_) Pure water boils at 100 oC; sea water boils at a higher temperature(_) kf and kb for the same solvent are generally different (o) Molality includes the moles of solute and the volume of solvent 4. 6/6 points Last Response | Show Details All Responses Notes The following questions all apply to the experiment "Freezing Point Depression."a. What solvent is used for this experiment? (_) water (o) stearic acid (_) ethylene glycol (_) methanol (_) acetone (_) lauric acid b. kf for this solvent is 4.5 oC/m. c. The solute in Part B of the experiment is: (o) lauric acid (_) methanol (_) acetone (_) water (_) ethylene glycol (_) stearic acid d. The molecular mass of this solute is 200 g/mol. e. According to the directions for this experiment, select all the pieces of equipment you will use for this experiment. [_] test tube [_] spectrometer [_] a computer [_] thermistor [x] graduated cylinder [x] spatula [x] hot plate [x] crystallization dish [x] beaker [x] digital thermometer [x] tongs5. 6/8 points Last Response | Show Details All Responses Notes In the Freezing Point Depression lab, you will calculate the colligative molality of the solutions you produce, the freezing point depression and the predicted boilingpoint of the resulting soltions. This question will give you practice doing this before you come to lab.If you use 10.900 g of solvent (FP= 82.7 °C; and Kf = 4.7 °C/m) and 0.730 g of solute (molecular mass = 127.76 g/mol), a. How many moles of solute have you used? .0057 molesb. What is the colligative molality of the solution formed? .524 m c. What is the predicted freezing point depression, Tf? 2.467 °Cd. What is the predicted freezing point of the soltuion formed? 4.71


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NCSU CH 202 - Lab 03 Prelab

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