Final answer:
To calculate the volume of a 0.9% NaCl solution containing 5g of NaCl, we use the m/v % formula. For the given solution percentage, we set up a proportion and solve for the volume, resulting in 555.6 mL as the needed volume to contain 5g of NaCl.
Step-by-step explanation:
To solve the problem of calculating the volume of a 0.9% (w/v) NaCl solution that contains 5g NaCl, we need to use the definition of mass/volume percent (m/v %). The formula for m/v % is:
m/v % = (mass of solute in grams/volume of solution in mL) x 100%
Given a 0.9% NaCl solution, this means that there are 0.9 grams of NaCl in every 100 mL of solution. We can set up a proportion to find the volume of the solution that contains 5 grams of NaCl:
0.9g NaCl / 100 mL = 5g NaCl / V mL
To find V, we cross-multiply and solve for V:
V = (5g NaCl x 100 mL) / 0.9g NaCl
V = 500 mL / 0.9
V = 555.56 mL, which can be rounded down to 555.6 mL due to significant figures.
Therefore, the final UNIT for this problem would be (b) mL.