Pharmaceutical Calculations

How many millimoles of Na are contained in 50ml 0.9% NaCl solution?

Relative Molecular Mass (Na = 23) (Cl = 35.5)

The answer is meant be 7mmol but I cant figure it out. Please help

Reply 1

TX27

The concentration of NaCl in a 0.9% solution is 0.9 g/100 ml. The molar mass of NaCl is 58.44 g/mol.
calculate the amount of NaCl in 50 ml of 0.9% solution:
So do 0.9 g/100 ml x 50 ml = 0.45 g NaCl
Then calculate the number of moles of NaCl in 0.45 g:
0.45 g / 58.44 g/mol = 0.0077 mol NaCl
Since NaCl dissociates into Na+ and Cl- ions in solution, multiply the number of moles of NaCl by 1 to get the number of moles of Na:
0.0077 mol NaCl x 1 mol Na / 1 mol NaCl = 0.0077 mol Na
Convert the number of moles of Na to mmol:
0.0077 mol Na x 1000 mmol/mol = 7.7 mmol Na
Thus, there are approximately 7.7 mmol of Na in 50 ml of 0.9% NaCl solution or u can keep it at 7 mmol or 8 depending on ur rounding during the steps.
I hope this helped a lil and feel free to message me privately and ask anymore questions. :smile: