How do you calculate the effective quantity (g) of sodium chloride related to tonicity in 100 mL of an intravenous fluid labeled "5% dextrose in 0.45% sodium chloride"?

Question

What steps and formula should be used for a problem like this, and what is the overall rationale?

Answer 1

As given this problem has no solution. In order to solve this you would need to know the convention for how percent solutions are reported in pharmacology. Your options are weight/volume (w/v), weight /weight (w/w) and volume / volume (v/v). I am going to assume weight/volume as NaCl is a solid making v/v inconvenient and w/w is more error prone in critical medical environments. Once you know that the solution is w/v you realize that you have a complex mixture where you dissolve the dextrose after preparing the NaCl solution. From there you simply find g NaCl / 100 mL H2O = % NaCl w/v.