BEHS Chemistry |
|
Assignment directions for a project using freezing various salt water solutions Chem Projects Research Team CheMystery Labs 380 South Buzz Blvd Bee Hive, UT 84302 Dear Team: The Director of CheMystery Inc. wants your research team to discover how the amount of salt affects the freezing point of water. The company has a budget of $50,000 to answer this question. Before you begin your work, I will need the following information from you so that I can approve your work. The planning space for these items is found in your project packet. Ø a detailed summary of your hypothesis, experimental design table, a plan for the procedures along with all necessary data tables Ø a description of necessary calculations Ø an itemized list of equipment with costs and chemical with their costs, include labor costs of $80 / hour and cost for laboratory space $10,000/day, and a standard disposal fee of $2000 / gram of material. After you complete the analysis, prepare a report for the Director and Officers of CheMystery Inc. Remember that this report will be seen by a variety of people, so be certain it projects the image we want to present. The items that should be included in the report are found in your project packet. Good luck with the project. Please keep in close contact me as you proceed with the project. You will need a data verification signature, by having me observe one of the trials in the experiment. Sincerely Your teacher President and CEO CheMystery Labs Inc. Freezing Various Salt Water Solutions Background Information Solutions are homogenous mixtures that contain two or more substances. The major component is called You are probably familiar with some common uses of these effects: Antifreeze is used to lower the freezing ∆ T (the change in temperature) = Kf m
where change in the temperature (∆ T) is the freezing-point lowering or boiling-point elevation, K is a constant
and the molality of particles in solution is the same. For electrolytes, the molality of particles is equal to the molality of the electrolyte times the number of ions in the chemical formula of the compound. Procedures: Caution: THE THERMOMETERS ARE FRAGILE. DO NOT USE THE THERMOMETER AS A STIRRING ROD. USE ONLY A PLASTIC BEAKER OR BUCKET TO CONDUCT THIS EXPERIMENT.
1. Half fill a 600-mL plastic beaker or bucket with ice and cover it with about 20 grams of sodium chloride (rock salt). Stir 2. Half fill a test tube with distilled water and place it in the ice bath. Rinse the stirring rod and use it to stir 3. Mix up the various concentrations of salt solutions 4. Test using steps 1 and 2. CALCULATIONS: Calculate the correct freezing point using the formula below. CORRECT FREEZING POINT = 0oC minus ( 1.86 oC/M * Molarity of the solution * 2 ) Calculate the percent error using the formula inside the periodic table handout.
Other Ideas for Freezing Point Research Projects What effect does the type of salt have on the freezing point? What is more effective at lowering the freezing point of water salt or a commercial de-icer? At what temperature does the windshield washer fluid freeze? |