You are approached by a company that sells nanoparticles dispersed in a liquid. A droplet of their main selling product (SuperNano') is dropped onto the surface of water at room temperature. The surface free energy of the SuperNano"/water interface is 20 mJ/m and that of air/ SuperNano' interface is 45 mJ/m (i) Show that a droplet of 'SuperNano' will spread out on water. [10%) Adding a suitable surfactant increases both the 'SuperNanop/water and surface and air/'SuperNano free energies by 5% for every ppm of surfactant added. What is the minimum amount of surfactant in ppm that should be needed to prevent spreading? Explain your reasoning. [15%