Finding Equilibrium Constant, Kc

Topics: Chemical reaction, Chemistry, Concentration, Chemical equilibrium, Activity, Temperature / Pages: 4 (971 words) / Published: Jul 5th, 2013
Chemical Equilibrium: Finding equilibrium constant, Kc
1 Abstract Chemical reactions are accompanied with formation of products. A reaction can be reversible or forward according to the rate of formation of product. However, they do not reach completion and the mixture remains in equilibrium. This theory help us the study the existence of equilibrium constant, Kc. This constant is temperature dependent, and it must be calculated at given temperature. This equilibrium constant is used to improve the productivity of industrial products. Therefore, in our experiment Fe3+ ions and SCN- ions used to calculate the equilibrium constant Kc of formation of FeSCN2+ solution. FeSCN2+(complex ions) solution was able to absorb light due to the properties of complex ions, and that property helped us to determine the absorbance of different concentrations of that ions. We saw that absorbance increased as the concentration increased. Finally, we found the value of Kc, average value of different Kci and were 264.937M-1. The unit depends on the degree of species concentration.
2 Introductions:
Chemical equilibrium is said when the rate of formation of product is the same like the reverse reaction, the reaction do not be achieved and they remain in equilibrium. Kc is a constant at a given temperature, since temperature can affect rate, also it can affect Kc. The reaction between Fe3+ and thiocyanate ions is in equilibrium:
Fe3+ + SCN- FeSCN2+
Kc = [FeSCN2+]/{[Fe3+][SCN-]} 3) Objectives: To determine the equilibrium constant; Kc of the reaction between Fe3+ and SCN- ions 4) Materials:
Computer, Vernier computer interface, Logger Pro, Vernier colorimeter, 1plastic cuvette,5 test tubes of 20x150mm, thermometer, 0.0020M KSCN, 0.002M Fe(NO3)3( IN 1.0M HNO3),
0.2M Fe (NO3)3 (in 1.0M HNO3), 4 pipets, pipet bulb, tissues.
5) Safety measure: Wear goggle and gloves to protect against

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