Final answer:
To find the volume of seawater containing 7.5 g of sodium, one must first convert this mass to the equivalent mass of NaCl, then calculate the total mass of seawater needed, and finally use the density of seawater to find the corresponding volume.
Step-by-step explanation:
The question asks to calculate the volume of seawater that contains 7.5 g of sodium. First, we need to determine the mass of NaCl which corresponds to 7.5 g of sodium. Given that the atomic weight of sodium (Na) is approximately 23 g/mol, we can find the amount of NaCl using the ratio of the molecular weight of NaCl (58.44 g/mol) to that of Na. Once we have this mass, we can use the percentage of NaCl in seawater (3.5%) to find the total mass of seawater needed. Finally, given the density of seawater (1.02 g/mL), we can calculate the volume of seawater containing this total mass.