The rovibrational transition of^1H^35Cl with v = 0 rightarrow 1, J = 11 rightarrow 10 occurs at 2757.89 cm^-1, and the transition with v = 0 rightarrow 1, J = 10 rightarrow 9 occurs at 2779.07 cm^-1. From this information,

i) calculate the spring constant of the vibrational potential (assuming the harmonic approximation and rigid rotor approximation) and
ii) the equilibrium length of the HCl bond.