Question

3. The B4O5(OH)4 ion, present in 5.0 mL of a saturated Na B.Os(OH) solution at a measured temperature, is titrated to the bromocresol green endpoint with 5.28 mL of 0.182 M HCI Express all calculations with the correct number of significant figures. a. How many moles of B.Os(OH)are present in the sample? b. What is the molar concentration of B4Os(OH)4 in the sample? c. Calculate the Kop for Na2B4Os(OH)4 from these data. d. What is the free energy change for the dissolution of Na2B4Os(OH)4 at 25°C? R= 8.314 x 10 kJ/mol K.

Answer 1

Batoh + aut 4+₂ Bolx Bonorve solens point acidic end point By Of Congo + 2H ot +40 - 44B03 a). stolchomenic relation between Borde ron and that moles of By Of Com? = I x moles of it outch I x Mxv) HCl = 21 x 018 2m x 5.28 m2 x 153 ml ♡ b) ( Byg Conly) 2-) z 2 o-00048048 moles ~ 10.000480, moles] 2 10-480 x 103 moles moles of B004), 2- volume of saturated Soluna (in ) 0.480 4 18 moles s-omLx 103 L 2 mt 10-096M c) wą Cong Coll) - eNat & Byog Cont? when solublity of Borax es s' molar, then [nat) 2 25 [Byor Con?, ?-) 2 5. so solubility 2 Bygg(OH)2) = 0.096m. Ksp 2 (nat)? (Bygglon2-] 2 (25)² (s) – 45 =) Iesp? Ci 4x(0.09673 20.0035 - 3-5 *103

d-) T225°c = 2981 2 ono a . -RT ankop - 8-314x10 nt x2981 in Co-0035) molic T14.0 kJ) free energy for dissolution a 2 5.3058 TEJ suot