The effect of electrolyte concentration on the stability and coagulation of a colloidal suspension can be explained by the DLVO Derjaguin, Landau, Verwey, and Overbeek theory. According to this theory, the stability of a colloidal suspension is determined by the balance between attractive van der Waals forces and repulsive electrostatic forces between colloidal particles.When an electrolyte is added to a colloidal suspension, it affects the repulsive electrostatic forces between the particles. The electrolyte ions neutralize the surface charge of the colloidal particles, thereby reducing the repulsive forces and promoting coagulation. The higher the electrolyte concentration, the greater the reduction in repulsive forces and the more likely the colloidal particles will coagulate and settle out of the suspension.Experimental evidence:To demonstrate the effect of electrolyte concentration on the stability and coagulation of a colloidal suspension, an experiment can be conducted using a series of test tubes containing a colloidal suspension e.g., a dilute suspension of polystyrene spheres in water and varying concentrations of an electrolyte e.g., sodium chloride .1. Prepare a series of test tubes containing the same volume and concentration of the colloidal suspension.2. Add varying concentrations of the electrolyte e.g., 0.01 M, 0.1 M, 0.5 M, and 1 M NaCl to each test tube.3. Mix the contents of each test tube thoroughly and allow them to stand undisturbed for a period of time e.g., 24 hours .4. Observe the test tubes for any changes in the appearance of the colloidal suspension, such as the formation of aggregates or sedimentation of particles.Results:Upon observing the test tubes after the specified time, it can be seen that the colloidal suspension in the test tubes with higher electrolyte concentrations will show more significant coagulation and sedimentation of particles compared to those with lower electrolyte concentrations. This observation supports the conclusion that increasing electrolyte concentration promotes the coagulation and destabilization of colloidal suspensions.In summary, the stability and coagulation of a colloidal suspension are affected by the electrolyte concentration. Higher electrolyte concentrations reduce the repulsive electrostatic forces between colloidal particles, promoting coagulation and sedimentation. This conclusion is supported by experimental evidence using a series of test tubes containing colloidal suspensions with varying electrolyte concentrations.