How many saturated solutions of borax are to be titrated? Each saturated solutio

Question

How many saturated solutions of borax are to be titrated? Each saturated solutions of borax is prepared at a different temperature. How many trails per saturated solution are to be completed? What values are to be calculated from the data of the titrations? Several thermodynamic values are determined from the data plot of la K_ vs. 1/7 in Part D of the Experimental Processing dure in this experiment. Complete the following table for Trial 1 (See Report Sheet) for determining In and 1/T. Record the calculated values with the correct number of significant figures.

Explanation / Answer

I need to know the experimental procedure to answer questions 1-3. I will answer question since 4 since the question seems to have all the data required.

4) Write out the balanced chemical reaction between borax and HCl (you should have included the equation; I am using internet sources).

Na2B4O5(OH)4.8H2O (s) ------> 2 Na+ (aq) + B4O5(OH)42- (aq) + 8 H2O (l) …..(1)

B4O5(OH)42- (aq) + 2 H3O+ (aq) + H2O (l) ------> 4 H3BO3 (aq) ……(2)

Equation (1) gives the solubility of borax in water; the solubility product constant Ksp is given as

Ksp = [Na+]2[B4O5(OH)42-] (H2O doesn’t appear in the Ksp expression).

Equation (2) gives the neutralization of borax with HCl.

A. Standardization of HCl solution

8. Average molar concentration of HCl (mol/L) = 0.182

B. Preparation of borax solution

2. Volume of sample (mL) = 5.00

C. Analysis of borax test solutions

1. Burette reading, initial (mL) = 4.75

2. Burette reading, final (mL) = 10.03

3. Volume of HCl added (mL) = (final – initial) = 5.28

D. Data analysis

1. Temperature, T (K) = 295

2. 1/T (K-1) = (1/295) = 3.3898*10-3 (I will keep a few guard digits extra).

3. Moles of HCl used (mol) = (volume of HCl used for the titration in L)*(average

                                                     molar concentration of HCl in mol/L)

                                                = (5.28 mL)*(1 L/1000 mL)*(0.182 mol/L) = 9.6096*10-4

4. Moles of B4O5(OH)42- (mol) = (moles of HCl used in the titration)*(1 mole B4O5(OH)42-/2 mole HCl) (see equation 2 above) = (9.6096*10-4 mole HCl)*(1 mole B4O5(OH)42-/2 mole HCl) = 4.8084*10-4

5. [B4O5(OH)42-] (mol/L) = (moles of B4O5(OH)42-)/(volume of borax in L) = (4.8084*10-4 mol)/[(5.00 mL)*(1 L/1000 mL)] = (4.8084*10-4*1000)/(5.00) mol/L = 0.096096

6. Molar solubility of borax (mol/L) = (molar solubility of B4O5(OH)42-) (refer to equation 1 above) = 0.096096

7. Solubility product, Ksp = (molar solubility of Na+)2(molar solubility of B4O5(OH)42-) (refer to the expression for Kspabove)

Molar solubility of Na+ = 2*molar solubility of borax (refer to equation 1 above) = 2*0.096096 mol/L = 0.192192 mol/L

Ksp = [Na+]2[B4O5(OH)42-] = (0.192192)2*(0.096096) M3 = 3.5495*10-3 M3 3.55*10-3 M3

8. ln Ksp = ln (3.55*10-3) = -5.64

Related Questions

Navigate

• Browse (All)
• Browse H
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.