A coffee shop attendant added instant coffee powder to hot water until no more would dissolve. He added 30g of powder to 100 mL of water. What is the solubility of the instant coffee powder in hot water?
Solubility refers to how much of a solute can be dissolved into a solvent. In the current case, the solute is instant coffee and the solvent is hot water. The given information states that 30 gm of coffee powder was mixed in 100 ml of hot water and that no more coffee would dissolve in the hot water. Thus, the attendant reached the maximum solubility of instant coffee in the hot water. Solubility can be given in terms of mass per unit volume.
In this case, the solubility of instant coffee in hot water is 30 gm per 100 ml or 0.3 gm/ml of hot water. Note that this is the solubility in hot water. The corresponding solubility for cold water or hotter water may be different. In general, increase in temperature increases the solubility of a solute in water.
Hope this helps.