of pure gelatin is strictly required to be added to of a standard gold sol to just prevent its coagu — Surface Chemistry Chemistry Question

💡 Solution & Explanation

By Zsigmondy's definition, the Gold number is the mass in strictly milligrams ($\text{mg}$) of a protective colloid added to exactly $10\text{ mL}$ of standard gold sol. The given mass is $10^{-4}\text{ g} = 0.1\text{ mg}$ for $100\text{ mL}$ of sol. To find the amount for $10\text{ mL}$ of sol, we divide by 10: $0.1\text{ mg} / 10 = 0.01\text{ mg}$. Thus, the Gold number is $0.01$.