An analytical chemist prepared a chloride stock solution by adding 23.73 g of salt (NaCl) to 5.0 L of water. The fluorescence intensity of a 50 ml solution made from 10.00 ml of the stock and containing 0.01 mM of fluoroscein was measured to be 135 counts. The intensity of a 0.01 mM solution of fluorescein in water alone was 720 counts. The literature value for the fluorescence lifetime of fluorescein in water is 4.1 ns. Calculate the value of the dynamic quenching constant, ka, of fluoroscein V by Cl in water.
Answer: The above question can be solved using Stern Volner Equation: Fo/F = 1 + Ksv[quencher] Fo/F = 1 + kq€[quencher] Where Fo: fluoriscence intensity in absence of quencher              F: fluorescence intensity in presence of quencher              kq: quenching constant     ... See the full answer