Chem 1130 Lab Report Experiment 1 PDF

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Name: Lexie Rodriguez Lab Partners: Marissa O’Dell, Audriana Skdnecki, Jenn Wien CHEM 1130 TA: Temitope Nathan Date: 9/18/2018 Exp 1 - Equilibrium and Thermodynamic Study of Borax Objective: The purpose of this experiment is to find the concentration of B4O5(OH)42- using titration, then using that data to find Ksp, ΔGo, ΔHo, and ΔSo Procedure:  Use an eyedropper to take a 5 mL sample of the borax solution in the 45oC bath, add the solution to a graduated cylinder  Pour the solution into an Erlenmeyer flask as quickly as possible and measure/record the temperature of the solution  Get about 75mL of .125 M HCL in a clean beaker and record the exact concentration  Fill a buret with 50 mL of the HCL solution, record initial reading  Add three drops of bromocresol green indicator to the flask of borax, the solution should be blue in color  Titrate the solution with the HCL until the solution turns yellow  Repeat all steps for the solutions in the 35oC, 15oC, and 5oC baths and at room temperature Observations and Results: Type the notes from your laboratory notebook. This should include data tables and/or graphs. Do not cut and paste information you handwrote from the laboratory notebook – everything should be typed unless approved by instructor in advance. Titration Data for Borax Solutions Sample 45A 45B Actual Sample Temp 23 26.4 o C Initial Buret Reading 0 0 Final Buret Reading 8.5 8.2 Volume of HCL 8.5 8.2 (ML) Volume of HCL (L) 0.00 0.00 85 82

35A 26.6

35B 30.5

25A 26

25B 29.8

15A 23.4

15B 28.7

5A 24.4

5B 24.9

0 5.1 5.1

0 5.6 5.6

0 7.2 7.2

0 6.5 6.5

0 7.7 7.7

0 8.5 8.5

0 6.3 6.3

0 6.9 6.9

0.00 51

0.00 56

0.00 72

0.00 65

0.00 77

0.00 85

0.00 63

0.00 69

Show Calculations – It is very important to show your work and HOW you reach your conclusion. The method of problem solving is often more important than the accuracy of the

answer, as long as you can account for error. If you use Excel for computation, be sure to show the formula used. You may leave space in the lab report to hand-write (in pen) a sample calculation and chemical equations for different assessments. Include units and show cancelation of units when using dimensional analysis. Consider significant figures as well. Table II: Thermodynamic Data

Sample 45A 45B 35A 35B 25A 25B 15A 15B 5A 5B

Vol. HCl

Conc. B4O5(OH)4

.0085 .0082 .0051 .0056 .0072 .0065 .0077 .0085 .0063 .0069

.000531 .000513 .000319 .000350 .000450 .000406 .000481 .000531 .000394 .000431

Ksp

Ln(Ksp)

Temp (˚C)

Temp. (K)

1/T

5.989E-10 5.400E-10 1.300E-10 1.715E-10 3.645E-10 2.677E-10 4.451E-10 5.989E-10 2.447E-10 3.203E-10

-21.236 -21.339 -22.763 -22.486 -21.732 -22.041 -21.533 -21.236 -22.131 -21.862

23 26.4 26.6 30.5 26 29.8 23.4 28.7 24.4 24.9

296.15 299.55 299.75 303.65 299.15 302.95 296.55 301.85 297.15 298.5

3.377E-03 3.338E-03 3.336E-03 3.293E-03 3.343E-03 3.300E-03 3.372E-03 3.313E-03 3.365E-03 3.350E-03

2-

ΔG (J) (Using Eqn. 1-6) 52286.498 53143.898 56728.162 56766.944 54050.377 55515.246 53089.971 53293.460 54674.748 54255.559

ΔG (J) (using Eqn. 1-7)

ΔH (kJ/mol)

ΔS (J/ (mol K))

2332.383 2350.186 2351.233 2371.653 2348.0914 2367.988 2334.478 2362.229 2337.619 2344.688

781.742 781.742 781.742 781.742 781.742 781.742 781.742 781.742 781.742 781.742

-5.236 -5.236 -5.236 -5.236 -5.236 -5.236 -5.236 -5.236 -5.236 -5.236

Sample Equations (Using sample 45A): [B4O5(OH)42-] = .0085 L HCl x

.125 mol HCl 1 mol borax x 2 mol HCl 1L

= .000531 mol borax

Ksp = 4[.000531]3 = 5.99E-10 T(K) = 23oC + 273.15 = 296.15 K 1/T = 1/296.15 K = 3.377E-03 J ΔG = (-8.314 )(296.15 K)(5989E-10 mol) = 52286.498 J mol∗K KJ J )-(296.15 K)(-5.236 ) = 2332.283 J ΔG = (781.742 mol mol∗K

ln Ksp v. 1/T -2.00E+01 3.28E-03

3.30E-03

3.32E-03

3.34E-03

-2.05E+01

ln ksp

-2.10E+01 -2.15E+01 f(x) = 6499.43 x − 43.54 -2.20E+01 -2.25E+01 -2.30E+01

1/T

3.36E-03

3.38E-03

3.40E-03

Discussion and Conclusion: The higher the volume of HCL, the more concentrated the B4O5(OH)42-. The higher the concentration the more ions which means a higher magnitude for Ksp. Error that might have occurred include: incorrect temp reading, not stopping the titration in time, and calculation errors. Questions: 1. A) Has no effect on the system B) shifts away from equilibrium because more concentrate needs to be used up. 2. The reaction is endothermic because ΔH is greater than zero. 3. When the temperature increases the equilibrium should increase to because it is an endothermic reaction and is taking in heat and energy to increase what the equilibrium can be. 4. My values are much different do to error in the experiment process, and/or error in the calculations....