This question is about an experiment to investigate the effect of temperature on the equilibrium constant, K₁, of the reaction shown. Fe³⁺(aq) + SCN⁻(aq) ⇌ FeSCN²⁺(aq) The data collected is used to determine the value of the enthalpy change of the reaction. To set up the equilibrium, aqueous iron(III) nitrate, Fe(NO3)3(aq), is mixed with aqueous potassium thiocyanate, KSCN(aq). Aqueous iron thiocyanate ions, FeSCN²⁺(aq), have a red colour. A colorimeter is used to measure the absorbance of the reaction mixture. A calibration graph can then be used to determine the concentration of FeSCN²⁺(aq) in the reaction mixture. [Table 2.1] shows the solutions for the experiments. Table 2.1 | solution | ion | concentration/mol dm⁻³ | |---|---|---| | A | SCN⁻(aq) | 0.00920 | | B | SCN⁻(aq) | 0.00200 | | C | Fe³⁺(aq) | 0.00200 | | D | Fe³⁺(aq) | 0.500 |