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Kunal Kanwar, Celine Loh, Miloni Shah General Chemistry II/Lab Dr. Pitteloud April 15th, 2019

The Dissolution of Borax Data/ Results: 1

2

3

4

5

6

7

8

9

10

11

12

5

5

5

5

5

5

5

5

5

5

5

5

Temperature of 69.9 sample (C)

63

48

47.5

24.5

6

65

60

40

30

23

3

Initial volume (ml)

0

7.7

18.1

0

14.8

8.2

0

0

0

0

0

0

Final volume (ml)

7.7

18. 1

29.8 8.2

20.9 14.8

8.6

8

7.5

7.3

7

7.4

Volume of HCl 7.7-0= (ml) 7.7

10. 4

11.7

8.2

6.1

6.6

8.6

8

7.5

7.3

7

7.4

Temperature (K)

69.9+273= 342.9

33 6

321

320. 297. 5 5

279

338

333

313

303

296

276

1/T (K-1)

1/342.9= 0.00292

0.0 02 98

0.00 0.00 0.00 312 312 336

0.00 0.00 0.0 358 296 03

0.00 0.00 0.00 0.00 319 33 338 362

Moles HCl (mol)

0.2* (7.7/1000) =0.00154

0.0 02 08

0.00 0.00 0.00 234 164 122

0.00 0.00 0.0 132 172 016

0.00 0.00 0.00 0.00 15 146 14 148

Moles borax (mol)

0.00154/2= 0.0 0.00077 01 04

0.00 0.00 0.00 117 082 061

0.00 0.00 0.0 066 086 008

0.00 0.00 0.00 0.00 075 073 07 074

[Borax] (mol/L)

0.00077/ (5/1000)= 0.154

0.2 08

0.23 0.16 0.12 4 4 2

0.13 0.17 0.1 2 2 6

0.15 0.14 6

Volume of sample (ml)

0.14 0.14 8

Molar solubility, BORAX

0.154

0.2 08

0.23 0.16 0.12 4 4 2

0.13 0.17 0.1 2 2 6

0.15 0.14 6

Ksp

4(0.154)3= 0.014609

0.0 35 99 6

0.05 0.01 0.00 125 764 726 3 4 2

0.00 0.02 0.0 92 035 163 84 4

0.01 0.01 0.01 0.01 35 244 097 296 7 6 9

ln Ksp

ln (0.014609) 3.3 =-4.226114 24 35 7

2.97 100 8

4.68 856 6

-ΔH°/R (slope)

-1330.9

ΔS°/R

0.1294

4.03 737 2

4.92 490 8

3.89 4.11 448 145 8

4.30 506 6

4.38 615 2

0.14 0.14 8

4.51 204 4

4.34 533 5

(y-int) ΔH° (kJ/mol)

-( -1330.9 * 8.314/1000)= 11.07

ΔS° (J/mol K)

(0.1294* 8.314/1000)= 0.00108

ΔG° (kJ/mol)

11.07- (298*0.00108)= 10.749

Post Lab: 1-4 1. If no desiccator is available, then the reported molar concentration would be reported as too high. This can be said as the humidity in the room causes the sodium carbonate to have condensation thus causing a higher mass of sodium carbonate. The molar concentration of the HCl would be too high because as the mass increases the molar concentration increases. 2. a) By overshooting, more acid is added than needed which calculates more moles of base than existent in the original solution, so the reported acid concentration is lower than it actually is. b) The value of moles of B4O5(OH)42- would be too high because more acid is being used, which indicates more base being existent. 3. The solid borax would cause a concentrated solution, which would require more hydrochloric acid to equalize it. This addition of more HCl would cause the solubility product to be higher because the molar solubility would be greater.

4. The value of Ksp would be too low. A lower amount of standardized HCl would be needed to titrate since the solid borax is dissociated more. Thus, the concentration of standard HCl solution required is less results in lowering the molar solubility and lowering the Ksp....