Question

Making the simplistic assumption that the dissolved NaCl(s) does not affect the volume

of the solvent water, determine the constants m and b in the equation Molarity = m⋅density + b that relates the NaCl molarity to the NaCl(aq) density. Take the density of water to be 1.00 g/mL and the molar mass of NaCl to be 58.5 g/mol.

Answer 1

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if we assume volume NaCl + volume H2O = volume H2O.. i.e.. NaCl does not effect volume

therefore.. the units of..
.. M = moles NaCl / L solution ≈ moles NaCl / L H2O
.. density = grams NaCl / L solution ≈ grams NaCl / L H2O
again.. that is our assumption

so we can readily see that
.. M = (1 mol NaCl / ___g NaCl) x (__g NaCl / L H2O) + 0
ie..
.. M = (1 mol NaCl / 58.5g NaCl) x density solution + 0

so.. we would expect..
.. m = 0.01709 mol / g
.. b = 0