Determination of the identity of an unknown liquid Essay

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

Procedure: I used a ruler, thermometer, and scale to take measurements. I used a graduated cylinder, short step pipet, scale, and ruler to determine volume and density. I used a volumetric flask, graduated pipet, pipet bulb, scale, and glass beaker to determine concentrations and densities of various dilutions.

Experiment 2 “Density” was about how to measure the mass and volume and determine the density of water, alcohol, and a solid. For this lab, we begin by calculating the mass of empty graduated cylinder and the mass of 25 mL of tap water. After taking the mass of water and cylinder, we record it on “Density of Water: Data Table”. Since we did not have enough time of complete the whole lab, so we skipped the procedure to measure the density of alcohol. We jumped to the next procedure, which was density of a solid. For that we used a copper and it density 8.95. For this lab, my partner and I did not make any mistakes or errors. But, for better improvement I think we should have more time to complete the whole lab. I felt like we was rushing through

Procedure: Using distilled water, premeasured containers and objects determine displacement of fluids and density of objects. Use ice and heat measure temperatures in Celsius, Fahrenheit and Kelvin.

9. The accepted value for the density of water is 1 g/mL and the accepted density for isopropyl alcohol is 0.786 g/mL. Determine the percent error between your calculated densities and the accepted values for both water and isopropyl alcohol. Record the percent error in Data Table 4.

We found the density of the unknown object #6 to be 5.9(g/mL). We then use the table to identify the metal, and the result is that the name of the metal is zinc. Since the density of zinc is 7.14 and that is the closes number to our density, we determine that our unknown object is zinc. Our average density for the unknown liquid #5 is .779(g/mL). The closes density of a known liquid on the table is .792(g/mL), so we concluded that our liquid #5 is cyclohexane which has a density of

A. Water boils at 100°C at sea level. If the water in this experiment did not boil at 100°C, what could be the reason?

2. The least precise measurement was the temperature but more specifically the freezing points of the solutions and solutes. Due to the freezing point only having two significant figures, the data is limited to two significant figures as well.

The volume and the boiling point of each collected sample was recorded in a table (for Fractions A, B, and C). The data in the table was converted into a graph (both of which are attached to the back of the report). There is, like in all experiments, an ideal set of data. In this experiment, if the distillation for the unknown mixture (which has two compounds) was done properly, the temperature vs. volume graph should show two plateaus for temperature. (See hand drawn graph attached on back). We look at the plateau temperatures because they are essential to find out what the unknown compounds are. This is because the plateau temperatures show us the boiling point ranges for the unknown compounds. In addition, as shown in the table and calculations attached to back, the volume of the collected sample can be utilized to figure out a ratio of the compounds. But, of course, since ideal and pure samples were not collected, the ratios that are calculated are just estimates. There is one plateau for the boiling point of both lower and higher boiling point compounds. The lower boiling point plateau comes first. The transition phase that occurs between the first and second plateaus was collected. This transition phase represented the mixture of the two compounds in the experiment. If the experiment yielded ideal results, sample A would show to be consisted of primarily the lower boiling point compound. This would be the case up to the point when the temperature is raised to match the boiling point of the higher boiling point compound. The compound is sample C. During the experiment this sample was gathered in a falcon tube. But there is some error in my results. Some of the reasons why there was error in the experiment are stated. I boiled Fraction A for too long, the boiling rate was too high, or a combination of these errors occurred. If the boiling rate is too fast, the side arm will heat up as the

My calculated volume values were found by using the Charles’ Law formula: V1/T1=V2/T2. My Trial A values (20 mL and 293.15 K) were the V1 and T1 values. The temperatures measured in Trials B, C, D, and E were the T2 values. The quantitative relationship between the volume and the absolute temperature of a gas is summarized in Charles’ Law. This law states that at constant pressure, the volume of a particular sample of gas is directly proportional to the absolute temperature. In other words, there is a direct relationship between temperature and the volume of gas. In an actual laboratory, it must be ensured that the hot water is below 50ºC. If it is not, the sealed syringe will soften and it could explode.

In the third stage of this experiment, the density of a liquid was determined and compared to known standards. A 100ml beaker was filled to about half-full with room-temperature distilled water. The temperature of the water in ◦C was recorded in order to compare to known standards later. A 50ml beaker was then weighed on a scale in order to determine mass and recorded. A sample of the distilled water with an exact volume of 10ml was then placed in the 50ml beaker using a volumetric pipette. The 50ml beaker with the 10ml of water was then weighed again and the initial mass of the beaker was subtracted from this mass to obtain the mass of the 10ml of water. With the volume and the mass of the water now known, density was calculated using d = m/V and recorded in g/ml. This process was then repeated to check for precision and compared to standard values to check for accuracy. Standard values were obtained from CRC Handbook, 88th Ed.

The volume of a small test tube and a thin-stemmed pipet were determined in this section of the lab. Water was poured into a small test tube until the water reached the very top edge of the test tube. The test tube was then emptied into a plastic 25 mL graduated cylinder and volume was measured and recorded into data table 3. A think-stemmed pipet was completely filled with water. Drops were carefully counted and emptied into the empty plastic 25 mL graduated cylinder until the water level reached 1 mL. The number of drops in 1 mL was recorded into data table 3. The thin-stemmed pipet had a total volume of 4 mL and that was also recorded into data table 3.

The boiling points of the ionic and covalent compounds do not show any clear sign of differentiation. Because ionic compounds have high boiling points, the expected results were that unknown 1 and 2 were going to boil last. According to the results, it was mostly it was mostly the results of unknown 1 that was incorrect. Because the beakers with the 4 different unknowns in each of them were right beside each other, the heat of the surrounding beakers may have transferred to the beaker beside each other. Furthermore, all the beakers on the hot plate might have made the process of boiling take longer. Because the center of the hot plate might have had the most heat, heating each beaker individually might have resulted in more accurate results. Also, when instructed to fill up the beaker halfway, it was not clearly implied that the intended amount of water was supposed to be 25mL, not 35mL. The ratio between the amount of distilled water and the unknown substance may have also hindered the results. The actual boiling point for sodium chloride

Despite measuring the same amount of solution for all three volumetric glassware, it was revealed in this experiment that different glassware will give fluctuating recordings due to the different calibrations found within each glassware. It was deemed that the Buret provides the most precise density value among the three glassware utilized in the experiment. The Buret accumulated 0.34 % difference indicating high precision. The least precise data came from the graduated cylinder. The graduated cylinder had a percent difference of 1.37% which was the highest percent difference recorded for the experiment. There are a number

The purpose of this experiment is to identify an unknown substance by measuring the density and boiling point. I will be able to conclude which substance is my own from a list of known options stating what its real boiling point and density is.