Introduction: Freezing point depression is a colligative property that calculates the decrease of the freezing point when any solute is added to a solvent. When determining changes in freezing point, solute concentration is measured in molality which is moles of solute per kilogram of solvent. The concentration unit moles per kilogram is temperature independent, because mass does not vary with temperature. The decrease in freezing point of the pure solvent is proportional to the molality of the particles of solute and is represented by the following equation: ΔTf=Kf ۰ m. By finding the freezing point of an unknown solution, it provides an opportunity to determine the molar mass of the unknown substance. Also, in this experiment a heating …show more content…
To prepare for the lab, fill one 600 mL beaker ⅔ full with tap water (roughly 400 mL full) and place on a hot plate with a thermometer. This beaker’s temperature needs to stay constant at 60℃ so the hot plate settings may need to be adjusted throughout the lab. Next, fill the 1000 mL beaker ⅔ full with cool tap water (roughly 700mL full) and place a thermometer in it. Set this beaker aside and maintain a temperature of roughly 25℃. Place the test tube of benzoic acid/lauric acid in the 60℃ water on the hot plate and when the solid solution begins to melt place the thermometer that was in the water into the test tube. Continue to heat the solution until it reaches about 55℃. Using the test tube holder, transfer the liquefied solution tube to the 25℃ water and record the temperature at 30-second intervals using a clock or stopwatch using a pencil until the solution reaches 35℃ or close to the temperature due to experimental error. While cooling, gently stir the solution using the thermometer until the solution begins to solidify. Once all the data is collected, reheat the solid solution tube in the warm water until it melts and remove the thermometer and wipe it off to avoid the solution adhering to the thermometer. After the data has been recorded, clean-up the lab station and put away the lab …show more content…
It also confirmed the idea that molar mass of a solution could be determined through the freezing point depression formula as long as one knows the freezing point depression constant of the solvent used, the mass in kilograms for the solute-solvent mixture, and the change in freezing point from the addition of a solute. Lab Questions: What is the freezing point for lauric acid? What is the melting point for lauric acid? The freezing point for lauric acid in this experiment was 43℃. The melting point for lauric acid in this experiment was 50℃. Explain what is happening during each section of the graph for both cooling and heating in terms of particle motion and energy. When heat is added to a substance the particles in the substance vibrate faster and when vibrate faster the space between the particles increases. The hotter it gets the more the object expands and takes up more space. When a substance is cooled the particles vibrate less causing them to constrict and take up less space. The colder the solution gets the more the particles compact and
The temperature probe was then quickly cooled to room temperature. When this was achieved, the hot water was immediately transferred into the calorimeter. This method of keeping the temperature probe cooled before measuring a new temperature was repeated throughout the entire experiment. Temperature data was collected for 180 s while swirling the temperature inside the calorimeter. The calorimeter still contained the warm water.
If I had a chance to do this experiment once again. I would improve this experiment by actually testing, whether temperature affects the rate of reaction of the alka seltzer tablet, by having the water be hot, warm and cold, and determine at which temperate does the tablet dissolve faster. I could also change the amount of water I used during the experiment, as I only used 100ml of water in a 400ml beaker. I would also change the temperate of the room. A further investigation can study how temperature affects the rate of reaction between water and alka seltzer tablets.
These results a somewhat inaccurate due to the fact that when the solutions were actually freezing is difficult to tell. Some solutions froze slowly and showed a plateau, while others
In the second portion of this experiment we will keep the temperature constant and divide the ½ tablet of Alka- Seltzer into 2 pieces ,3 pieces and an unbroken ½ tablet. It is my belief that Alka-Seltzer
Introduction The intent of this experiment is to understand how hot and cold water interact with each other by combining clear hot water and black ice cold water. I hope to learn more about how hot and cold water interact with each other. As of now, I know that cold water is denser than hot water. Knowing this I formed my hypothesis.
Place the lid back on the Styrofoam cup. 8. Record the temperature every 30 seconds for a total of 10 minutes. Chemicals Quantity Sodium chloride powder (NaCl(s)) 20 g Water 500 ml Page 5 of 7 9. Repeat steps 4 to 8 for a total of 3 recordings.
Purpose: The purpose of this experiment was to determine the molar mass of unknown #43 using the derived freezing point depression. To obtain the freezing point depression, t-butyl alcohol was placed in a cold-water bath and frozen solid for a total of two runs. Then, unknown #43 was dissolved in t-butyl alcohol and placed in a cold-water bath until frozen solid. This process was repeated for a total of three runs, with the first two runs containing half of the unknown, and the last run containing the full amount of unknown.
Label the test tubes with hot Using a test tube holder put the test tubes into the beakers. Place 2 test tubes with the hot label in the hot water and the other 2 with the cold label in the ice. Let the test tubes be in the beaker for 5 minutes. Take all the test tubes out of the beaker and drain the water. Then add 3 ml of hydrogen peroxide using a pipette to all the 4 test tubes.
Materials: The materials that I will be utilizing during these experimentations are three to four ice cubes, one cup for measuring, six unblemished cups, one stopwatch, one hot water source, three tablets of Alka-Seltzer, one thermometer that measures from negative
Weighed 1 gram of NaC2H3O2 and mixed it with ionized water. Boiled 12 mL of 1.0M Acetic Acid added into a beaker containing the sodium carbonate on a hot plate until all the liquid is evaporated
37.8 °C and 36.3 °C 30-40 °C 3. 41.7 °C and 40.2 ° C 40-50 °C 4. 50 °C and 48 ° C 50-60 °C Average temperatures: (37.8+36.3)/2=37.05 °C (41.7+40.2)/2=40.95 °C (50+48)/2=49 °C Table 1 -The values of experiment Temperature (°C) Density (kg/m3) 26.5 995 37.05 992.5 40.95 991 49 990 70 984.856 80 982.524 90 980.272 100 977.93 Table 2. The values in steam table Temperature (°C) Density (kg/m3)
Materials 1 calibrated thermometer, 1 scale that reads mass, 2 Styrofoam cups, 1 small lead sinker, boiling water in a beaker, 1 pair of kitchen tongs, 1 small cooking pot, stove top, distilled water, and 1 pair of safety goggles (I did not use a cork stopper). III. Procedure First, the beaker
Purpose/Introduction The process of recrystallization is an important method of purifying a solid organic substance using a hot solution as a solvent. This method will allow the separation of impurities. We will analyze Benzoic Acid as it is dissolved and recrystallized in water and in a solvent of Methanol and water. Reaction/Summary
Aim: To find out the relationship between the greater concentration of sodium thiosulfate when mixed with hydrochloric acid and the time it takes for the reaction (the time it takes for the solution to turn cloudy) to take place and to show the effect on the rate of reaction when the concentration of one of the reactants change. Introduction: The theory of this experiment is that sodium thiosulfate and hydrochloric acid reach together to produce sulfur as one of its products. Sulfur is a yellow precipitate so, the solution will turn to yellow color while the reaction is occurring and it will continue until it will slowly turn completely opaque. The reaction of the experiment happens with this formula: “Na2 S2 O3 + HCL =
When a solid dissolves in a liquid, it then changes its physical state (from solid to liquid) by melting. Heat is needed to break the bonds holding the molecules in the solid together and at the same time; heat is given off during the formation of new bonds between solute and solvent. Results Table1. Results for titration of benzoic acid with NaOH at 20◦C V(NaOH) ml V(C_6