- #1
p3t3r1
- 33
- 0
Hi there, this is a not a homework question but rather question about the theory behind this problem.
Say if someone asks you to calculate the number of moles in 20 ml of a 1M NaOH solution, I would usually say it is going to be 20 mmol as you do 20 ml/1000 ml/L x 1M = 0.02 moles = 20 mmol.
However, if you consider the density approach, 1M of NaOH has a density of 1.04 g/ml so 20 ml is 20 x 1.04 g = 20.8 g/40 g/mol (MW of NaOH) that is going to yield 520 mmol of NaOH in 20 mll of 1 M NaOH.
Obviously the density approach give a number that makes no sense. I am just wondering why the density approach is not correct.
Cheers.
Say if someone asks you to calculate the number of moles in 20 ml of a 1M NaOH solution, I would usually say it is going to be 20 mmol as you do 20 ml/1000 ml/L x 1M = 0.02 moles = 20 mmol.
However, if you consider the density approach, 1M of NaOH has a density of 1.04 g/ml so 20 ml is 20 x 1.04 g = 20.8 g/40 g/mol (MW of NaOH) that is going to yield 520 mmol of NaOH in 20 mll of 1 M NaOH.
Obviously the density approach give a number that makes no sense. I am just wondering why the density approach is not correct.
Cheers.