Question

1. How can the K_c of two possible reactions be compared to determine which reaction is occuring?

2. How are the equilibrium moles of reactants(ions remaining in solution) calculated?

3. What are the equilibrium constant equations for the below reactions?

Fe³⁺ + SCN^- <==> FeSCN²⁺

Fe³⁺ + 2SCN^- <==> Fe(SCN)₂+

4. How are initial moles of a reactant calculated?

5. How is the concentration of the product determined for a reaction?

Answer 1

1. Feasibility of the reactions are checked by calculating the change in Gibb's free energy for the reaction. Change in Gibb's free energy for a reaction can be calculated by the relation, . If the value of Delta G is negative, the reaction is thermodynamically feasible while if it is positive, it is not feasible.

2. I'll answer 2 and 3 together. To calculate the equillibrium moles of reactants, we would have to use the value of equilibrium constant Kc and wirte the equation for the same.

Once we get the value of x (which is concentration of product) multiply it by volume to get the number of moles.

4. Initial moles of reactant need to be measured before adding it to the solution. Measure the wieght of the reactant added and divide by molar mass of the species to get number of moles. We also need to calculate concentration by dividing number of moles with volume because Kc is the equillibrium constant with respect ot concetrations. So the terms on the Right Hand Side of the equation of Kc are concentration terms.

5. Concentration of product are calculated similarly a given in 2 and 3.