Question

After completing Part A of this experiment, a student determines the slope of their calibration graph of absorbance versus [FeSCN2] to be 5140 M1. In Part B, a student combines 2.00 mL of a 0.00200 M solution of KSCN with 5.00 mL of 0.00200 M solution of Fe(NO,), and 3.00 mL of water. The following equilibrium is established. Fe (aq) + SCN (aq) FeSCN (aq) The absorbance of the equilibrium solution is measured as 0.246. What is the equilibrium constant for this reaction?

4. After completing Part A of this experiment, a student determines the slope of their calibration graph of absorbance versus (FeSCN2+] to be 5140 M". In Part B, al student combines 2.00 mL of a 0.00200 M solution of KSCN with 5.00 mL of a 0.00200 M solution of Fe(NO), and 3.00 mL of water. The following equilibrium is established. Fe+(aq) + SCN"(aq) FeSCN2+ (aq) The absorbance of the equilibrium solution is measured as 0.246. What is the equi- librium constant for this reaction?

Answer 1

( aation (4) According to Beer's lan Ar E (An absorbance lo E Molas absorpavily If are plot Molas concents- concentration (6) ou be path length x axist absorbancet) of photo cell. are will on xaxies get a linear equation & 1 cm (In generas) whose stope will be & Fiere, (FeS CN 2+] = c . it of & will & &=5140 [herever and self putting a = 0.246, de 3 ani, &- 5400 into anation (1) 0.246 - 5140 cх 1 cu S .: C 4 X 70 07 5190 Fest, TeNo 4 Before reaction initial concentrations are: Seeth, Mreno & Vressora Marolarity Vevolume Felag + Ve sentire 0.00 200 2 x S. rose (5 + 2+ 3 ay - 0.0olon SCN7im - esan & V x SCN Vrenons & VRSONtvo 0.0002mx 24 75 tot 3) = 0.0004

Feschlag) Now, at eauilibrium EERSCN2+] - 4.8x10-5 m. The Doction in Fest (0) & SCN (or) – Pritial: 0.00 0.0004 charge: G. 8 x8r - 4.88105 tanitim (ovs 4.8855) 10.ovor 89 2 4.8x10.5) 44.8805 4.8x18 = 9:52x70mm = 3:52 X7017 in Earriti briven contart. [FESCN2+] eg Kegu - [Fe3+] e [Sender 4.8 x10-5 9.52x1804 & 3:52x10-y - 143.2 Eariliklium constart of the reaction is 1432