Pt1420 Unit 6 Lab Answers

The freezing point depression constant for water that was experimentally determined in this analysis was 0.0479 °C/m, which was derived from the slope of the trend line in Figure 4. This is significantly lower than the constant stated in the literature of 1.86 °C/m.1 The freezing point temperature determined via cryoscopy should have been much lower in the high sucrose concentration solutions.

Abstract: This experiment introduced the student to lab techniques and measurements. It started with measuring length. An example of this would be the length of a nickel, which is 2cm. The next part of the experiment was measuring temperature. I found that water boils around 95ºC at 6600ft. Ice also has a significant effect on the temperature of water from the tap. Ice dropped the temperature about 15ºC. Volumetric measurements were the basis of the 3rd part of the experiment. It was displayed during this experiment that a pipet holds about 4mL and that there are approximately 27 drops/mL from a short stem pipet. Part 4 introduced the student to measuring

The experiment will start with two ice cubes. One will have nothing added to it, the other will have ½ tsp of salt sprinkled over it. Each will be separate on two different plates/containers. Time will be kept with a stopwatch, and notes will be taken throughout the experiment on the percentage of ice that has melted at certain points in time.

The cooling time caused error when calculating the moles of water because the actual result was seven moles instead of five moles which was what was calculated. The calculations could have been potentially miscalculated particularly due to the significant figures used in the data. The method for this experiment can be improved by maybe using another object rather than the crucible to allow a faster cooling time that way the calculations for the analysis have less of a chance of

Purpose: The purpose of this laboratory was to gain an understanding of the differences between the freezing points of pure solvent to that of a solvent in a solution with a nonvolatile solute, and to compare the two.

The scientist will be doing an experiment on how sugar and salt affects the boiling point and the freezing point of water.

The freezing point is the temperature at which a substance transfers from its liquid phase to a solid. Through comparison of the freezing points of a pure solvent (stearic acid), with those of a dilute solution, the molar mass of unknown solutes may be obtained. Water in its solid and liquid phase obtains a dynamic equilibrium (as their molecules convert between such phases at equal rates). Equilibrium can be disrupted through change in temperature or the addition of a solute. Increasing the temperature causes molecules to accelerate, prompting energy to be shifted to the solid surface and escape to the liquid phase. Increasing the quantity of solute in the liquid phase displaces some solution molecules that would have (if unimpeded) interacted

The primary goals of this experiment concern expanding upon the concept of molar mass and its applications to the study of chemistry (Beran, 2014). To this end, the effect of an unknown solute on the freezing point of a solvent, cyclohexane, was measured and noted in order to determine a positive or negative relationship between the two variables (Beran, 2014). Additionally, the molar mass of the nonvolatile and nonelectrolyte solid solute was ascertained (Beran, 2014).

My procedures were to compare the melting times of ice in cups of water, each with different amounts of salinity. I measured how long it took for ice to melt in each cup for a total of five times, and then found

2. The end of step 4 during the experiment creates the tripartite thermal structure within the lake substitute. This is composed of three parts called the epilimnion, the thermocline and the hypolimnion. The epilimnion represents the surface of the lake which experiences the most heat during the summer and has the highest temperature compared to the other parts of the thermal structure. The thermocline is the section of water that has the large exponential decrease in temperature. This is shown in figure 1 at the end of the heating phase, the temperature decreases by a large amount as the depth increases from 1cm to 9cm. Finally there is the hypolimnion which is shown in figure 1 in all phases as the cold part of the water column. This is the most unaffected part, as the solar radiation does not effectively penetrate that deep into the water hence the temperature stays almost constant. The

In order for water or milk to freeze, the temperature needs to be at or below 0ºC. In order to lower the freezing point of solution, different solutes can be added. A solution is created by dissolving a solute into a solvent, such as dissolving sugar (solute) into water (solvent). The process of decreasing a freezing point of a liquid by dissolving a solute into a solution is referred to as freezing point depression. The freezing point is a colligative property, which means that the freezing point depends on the number of solute particles dissolved in a solution. For example, CaCl2, which has three particles, would lower the freezing point of a solution more than NaCl would, which only has two particles (Helmenstine).

In order for water or milk to freeze, the temperature needs to be at or below 0ºC. In order to lower the freezing point of solution, different solutes are dissolved in solvents. When a solute is combined with a solvent, such as dissolving sugar (solute) into water (solvent), a solution is formed. The process of decreasing a freezing point of a liquid by dissolving a solute in a solution is referred to as freezing point depression. The freezing point is a colligative property, which means that the freezing point depends on the number of solute particles dissolved in a solution. For example, CaCl2, which has three particles, would lower the freezing point of a solution more than NaCl would, which only has two particles (Helmenstine).

The scientist's hypothesis is if there is more solute added to the water, then the water’s freezing point will decrease based on the number of grams of solute. To test the hypothesis the scientists will constantly add more salt/sugar to the water to see how much freezing point decreases per gram.

The purpose of this experiment is to learn concepts that explain the effect of solutes on the properties of liquids and to determine the molar mass of an unknown substance by using freezing points determined by a digital temperature probe. The molar mass of the unknown substance will be determined by measuring the freezing point of the lauric acid and lauric acid mixed with an unknown solute, then plugging those results into the freezing point depression equation (∆T = i*Kf*m). This equation will solve for the molality, number of moles, and the molecular weight of an unknown solute. The unknown substance will ultimately be determined based on matching the calculated molecular weight to the possible substance’s molecular weights.

During my master’s degree at Villanova University, I conducted an experimental research under the supervision of Dr. Jens O.M. Karlsson at “Biothermal Sciences Laboratory”. In this NSF funded research position, I designed, built, and optimized different types of glass capillary microfluidic devices, and utilized them for producing micro-emulsions. Subsequently, these micro-emulsions were used for investigating ice nucleation and crystallization in supercooled ultrapure water, for which I used high-speed imaging technique in conjunction with a powerful optical microscope and a cryo-stage. Figure 4 is a micrograph taken from one such video. Needless to mention, the knowledge gained from these experiments can open new doors to understanding mechanisms of damage in cells and tissue due to preservation at cryo-temperatures.