Experiment 4 - Lab Reort PDF

Preview

Summary

Lab Reort...

Description

EXPERIMENT 4 General Chemistry 1 SCC 2

TITLE OF THE EXPERIMENT Determining the Empirical formula of a Hydrate

Introduction The purpose of this experiment is to calculate or determining the empirical formula of a hydrate. In chemistry, formulas are used to illustrate the form of substances of compound or element. Element is a substance consisting of atoms which all have the same number of protons and different numbers of neutrons and different masses. Compound is the combination of two or more different chemical elements bonded together. There are two types of chemical bond in compound, are covalent and ionic bond of compound. Ionic compound is a compound formed by ions bonding together through electrostatic forces. Ionic compounds consist of

atoms in molecules that have charge ions with opposite charges. In this experiment, empirical formula gives the easiest number ratio of combined elements or compounds while molecular formula give the actual number of atoms of each element in a compound. Moreover, hydrate is a ionic compound that absorbs water molecules from either environment and includes them as part of its structure. These water molecules intact inside the compound and incorporated into the crystal structure of the compound or partially break up into their element and they are called water of hydration or water of crystallization.

Laboratory Equipment - Bunsen burner - Crucible - Tong - Balance - Clay triangle -Wire screen

Chemical or Compound - Barium chloride (BaCl2) Method / discussion Find the accurate result dependent of the mass measurement: Heating the crucible to constant mass - Light the Bunsen burner and set the flame to a lighter blue cone and placed the clay triangle on the ring stand and put the crucible on top of the triangle with the lip ajar. Make sure the crucible is dry and clean and heated for 5 minutes. - After 5 minutes moved the crucible with tong from the burner and placed it on wire screen. Waited for 10 minutes for the crucible to cooled with the lip covered and weighed the cooled crucible without the cover on a balance. Repeated the same thing for the second time and recorded the mass on the data sheet below. Data Heating the Crucible to constant Mass Mass of the empty crucible After first heating and cooling

12.6613 grams

After second heating and cooling

12.6608 grams

Determining the Hydrate’s water content

- Ionic hydrate sample is obtained and recorded on identification code on the data sheet. That is Barium chloride (BaCl2) - One gram of hydrate (BaCl2) was put in clean, dry crucible and weighed to record the mass. - The crucible with the sample was placed on the clay triangle with the tong and the lip on top and heated for 5 minutes. - After heating, place the crucible with the sample on wire screen with the cover and allow it to cool for about 10 minutes. - After cooling, weighed the crucible and the sample without the cover and recorded the data. And the same process was than the second time and recorded the mass on the data sheet. Data Determining the Hydrate’s water content Identification Code: BaCl2 Mass of crucible plus hydrate sample

13.664 grams

Mass of crucible plus hydrate sample: After first heating and cooling

13.514 grams

After second heating and cooling

13.5147 grams

The mass determined from the heating and cooling cycle was used in the mass calculations.

CALCUATIONS

1.Mass of original ionic hydrate sample

13.6613g - 12.6608g =1.0005g

2. Mass of the water given off by sample

13.664g - 13.5147g =0.1493g

3.Mass percent of water in the ionic hydrate

4. Mass of anhydrous compound

0.1497 g 1.0005 g

* 100% = 14.963%

1.0005g - 0.1493g = 0.8512g

5. Chemical formula of anhydrous compound

BaCl2

6.Molar mass of anhydrous compound

137.33g + (35.45 * 2)g = 208.23g

7. Number of moles of anhydrous compound

0.8512g *

8. Molar mass of water (H2O)

(1.00*2)g + 16.00g = 18.00g

9. Number of moles of water given off by sample 10. Ratio of moles of water divided by moles of anhydrous compound

11. Chemical formula of ionic hydrate

1 mol 208.23

= 4.0878 * 10-3

moles

1mol 0.1493g ¿ 18.00 g = 8.294 * 10-3 moles

8.294 * 10-3 : 4.0878 * 10-3 2.029 : 1.00

BaCl2 ∙ 2H2O

Discussion In the experiment the ionic hydrate used was Barium Chloride (BaCl2). The ionic hydrate was used to determining the calculations of the empirical formula of the hydrate water content. Heating and cooling a measured mass of BaCl2 was 0.8512grams, number of moles of BaCl2 was 4.0878*10-3 moles, the mass of water given by the ionic hydrate was 0.1493grams, number of moles of water given off

by the ionic hydrate was 8.294*10-3 moles and the ratio of moles of water divided by moles of ionic hydrate (BaCl2) was 2.029:1.00. Where 2.029 for the ionic hydrate and 1.00 for the water in the ionic hydrate. The experimental determined chemical equation of what happened when heated and cooling the ionic hydrate in crucible; (BaCl2 . H2O) → BaCl2 + H2O In similar process, how many grams of water are present in 3.00 grams of the ionic hydrate BaCl2? Grams of BaCl2 * 1 mole Molar mass of (BaCl2 + water) 3.00g * 1 mole = 0.0133 mole of water 208.23g+18.00g Molar mass of water * Mole of the water = Grams of water 1mole 18.00g * 0.0133mol = 0.239grams of water 1mole Conclusion Moreover, in the processed the heating helps to determine the mass of the water in the sample after cooling. These processed was important because, after heating there were no drastically changed of color but helps to know the precipitation that took placed. Although, our result was tad different when they were supposed to be, because there would had be some experimental masses errors that occurred during the experiment. The errors that affected the experimental mass was the weighed of the sample (BaCl2) and the mass of the water with the sample and without the sample, because the timing of the crucible was not enough for it to cool to the room temperature. These affected the measurement of the masses of experiment, but my confidence level on a scale of 8 out of 10. In the future it would be interesting to conduct the experiment again to figure out if altered numbers in the results were caused by these experimental errors or something else went wrong and did not notice. Reference Dionne Miller General Chemistry, Kendall Hunt publishing company in U.S. 2013....