# Freezing Point Lab

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Lena Katterman Amy Min Jennifer Brittle/Susanna Han Che 113-007 9/29/2014 The Relationship Between Concentration and Freezing Point Lab Introduction: In this lab the freezing point depression of water is going to be calculated. The freezing point depression is when a solvent is added to the solution, the freezing point will decrease. Then the correlation between sugar concentration and the freezing point can be observed. Sugar and salt may appear to look similar but are quite different. Sugar is made of carbon, hydrogen and oxygen. Salt is made of sodium and chlorine. This lab will also help observe the difference of the freezing point between a sugar solution and a salt solution with the same molality. Boiling point and freezing point are…show more content…
Mix throroughly. Carefully use tongs to place 150 mL of dry ice pellets into a 400 mL beaker. When the temperature is constant (-18-25 degrees Celsius), slowly put the NaCl solution over the dry ice. Set up measure net for each trail. Plug in the probe to the workstation. Turn on the work station and hit “Main Menu”. Next find the function keys to use the probe. For this experiment use temperate vs. time. Then hit “Calibrate”. To change the axis on the graph the button “set up” can change the limits. Use the “start/stop” at the beginning and end of each trial. Then find and record the temperature of the solution, rinse the probe well. Find and record the freezing point of water. Make 25 mL of 4 sugar solutions and the salt solution. Find the freezing point of 4 sugar solutions, each solution containing different concentrations of sugar. The maximum concentration is 2g per 25 mL of water. Record the mass of the solute and the solvent for each of the solutions. Record the concentration and molality for each of the solutions. Remember to clean the temperature probe between each trial. Materials needed: -salt -sucrose -250 mL flask -measure…show more content…
Solutions of 2 grams, 4, grams, 6 grams, and 8 grams sugar are in the 25 mL solvent. The freezing points can be found on the graphs that the measure net generates. By forming two different lines on the graph and finding the intersection the graph will show the freezing point. One line should be under the flat part of the graph and the other under the first decline of the curve. The hypothesis was proved because the solution’s freezing point was decreased with increased solvent. The salt sugar also has a lower freezing point than the sugar, with the same concentration. Both the salt and sugar solutions have a lower freezing point than the pure water, as expected. The percent error the calculation is =(|theoretical value-experimental value|)/(theortetical value) x 100. The percent error using the graphical value was 191.29%. The percent error using the results from the average temperature was 1589.40%. Some ways to keep the percent error down would to keep the ice bath at a constant temperature making sure it has the same amount of dry ice. Another way would be to make sure the measure net graph showed a good slope, showing a decline in temperature and then flattening off. Also the ice bath should be consistently stirred to make sure each trial has the same type of ice bath. It is also important to avoid using a dirty probe, it has to be cleaned thoroughly and carefully