Final answer:
To make a 9% salt solution, 9 grams of NaCl should be added to approximately 91 mL of water to achieve a total volume of 100 mL. This is based on the mass/volume percent concept used in preparing solutions in chemistry.
Step-by-step explanation:
To find out how many grams of salt must be added to 100 mL of water to create a 9% salt solution, we can use the concept of mass/volume percent (% m/v). This percentage indicates the mass of the solute (in this case, salt or NaCl) contained in a given volume of the solution. For a normal saline solution, which is a standard reference, there are 9.0 grams of NaCl in every liter (1000 mL) of solution, resulting in a 0.9% m/v concentration.
In order to prepare a solution with a higher concentration, specifically a 9% m/v, one must increase the amount of solute proportionally. The calculations would follow as:
Therefore, to prepare a 9% salt solution, one would add 9 grams of NaCl to approximately 91 mL of water, since the salt will contribute to the final volume, totaling 100 mL of solution. This process aligns with the principle in chemistry where the mass of solute must be subtracted from the total mass of the solution to determine the necessary mass of water.