Lab Report On Colligative Properties

I. LIQUID - Identification of an Unknown Liquid: Using the physical properties of Solubility, Density, and Boiling Point.

The objective of the experiment “Keeping it Liquid” was to figure out what it takes to keep a compound in a liquid form which caused a phase change. A phase change is when a substance changes from one state or phase to another. There are three main phases that normally occur and they are called Evaporation, Deposition, and Melting. Evaporation is where a liquid changes to a gas. An example of evaporation is when water drops form on the glass of a cold drink on a warm day. Deposition is where a gas vapor goes directly into the solid phase without becoming a liquid first. An example of Deposition often occurs on windows during the winter months. While Melting is where a solid turns into a liquid. Melting occurs when ice turn into a liquid when

Perform the following with three 0.05g samples of unknown and the following solvents: methanol, water and toluene

Other substances that dissolve in water also lower the freezing point of the solution. The amount by which the freezing point is lowered depends only on the number of molecules dissolved, not on their chemical nature. This is an example of a colligative property. In this project, you'll investigate different substances to see how they affect the rate at which ice cubes melt. You'll test substances that dissolve in water (i.e., soluble substances), like salt and sugar, as well as substances that don't dissolve in water (i.e., insoluble substances), like sand and pepper. Which substances will speed up the melting of the ice?

B. Claim: As we go from 1-butanol  sec-butanol  1-ter-butanol the dipole moments and the surface areas decrease. As we go from 1-butanol  sec-butanol  1-ter-butanol the steric hindrance increases. As we go from 1-butanol  sec-butanol  1-ter-butanol the ΔT (degree of evaporative cooling) decreases. As we go from 1-butanol  sec-butanol  1-ter-butanol the strength of the IMFs decrease.

The freezing point constant (Kf) of water is 1.86 °C m-1. Each mass amount and Van’t Hoff factor was calculated then analyzed in a table.

In order to fulfil the labs purpose, the lab was split into two parts. The first part consisted of measuring and determining the freezing point depression of the solution water. The second part consisted of measuring and determining the freezing point depression of a solution that consisted of water and an unknown solute.

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.

With time (t) on the x-axis and temperature (Celsius) on the y-axis, the exponential change could be easily observed. At the beginning of the laboratory the masses of the combined polypropylene test tube and 100 mL beaker were recorded by a digital electronic scale. A dry polypropylene test tube was obtained and approximately 2 mL of p-xylene was squirted into it with the use of a pipette. This was added to the beaker and weighed. 10 drops of toluene was then added and weighed again. The polypropylene test tube, which now contained 10 mL of p-xylene and 10 drops toluene was removed from the beaker and placed into a replica 100 mL beaker which was halfway filled with an ice water mixture. The temperature sensor, which was connected to the microlab application was placed inside of the polypropylene test tube and stirred rapidly around the outskirts of the bottom of the polypropylene test tube. The mixture began freezing, giving off an icy slush complex. Once the temperature appeared to have reached the nucleation point and leveled out at its freezing point, the application was stopped. This value was recorded in the laboratory manual. The temperature sensor was rinsed off then wiped, the beaker was re-filled with ice, and the test tube was put into the test tube rack to be thawed. Once thawed, this was discarded into the waste bin

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.

organic compound to dissolve (increase in entropy), a decrease in heat will then allow that

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

It is suspected that the freezing point is 64.1oC. Due to the short temperature plateau, It is difficult to determine if the freezing point occurs at during the interval (6:00-6:10). However, it appears to be have been the most reasonable determination for freezing point in comparison to the rest of the plot.

Colligative properties, such as boiling point and freezing point, are dependent on the amount of solutes added, not necessarily their identities (LibreTexts, 2018). A fascinating concept related to freezing points is Supercooling. Supercooling is a state where liquids do not form ice even when they reach temperatures below their normal freezing point; they are trapped in a metastable state (Esrf.eu, 2018). The best example of this is clouds at high altitudes: they contain tiny droplets of water that do not have seed crystals, and therefore do not form ice despite the low temperatures (Esrf.eu, 2018). The concept of freezing point depression is applicable in many parts of everyday life.

In class we examined all five liquids and identified the ones that froze. The five liquids were already in the freezer and froze by the time class started. Water and vinegar were frozen solid, while alcohol, and salty water