1. The problem statement, all variables and given/known data Suspension of Al2O3 particles and SiO2 particles are prepared seperately at a pH=6. If the two suspensions are mixed, what happen in view of the colloidal stability? 2. Relevant equations 3. The attempt at a solution Since the isoelectric point (IEP) of alumina and silica is pH 8-9 and 2-3 respectively, the pH 6 is the middle of their point. The alumina is under IEP, so it will have a positive charge. On the other hand the silica is above the IEP, so it will have a negative charge. If they are mixed, it will be flocculated because of unlikely charges. Am I right? If yes, can I say more? Thanks, Ryan.