A 1.5dm3 volume of 0.30moldm3 NaCl(aq) was mixed with a 2.5dm3 volume of 0.70moldm3 NaCl(aq). What is the final concentration of NaCl(aq)?

1 Answer
Oct 27, 2016

[NaCl(aq)]=0.55molL1.

Explanation:

Concentration = Moles of soluteVolume of solution.

We have to calculate the quantity of all the ions in solution, and then divide this by the total volume.

Moles of NaCl(i) = 1.50dm3×0.30moldm3=0.45mol

Moles of NaCl(ii) = 2.50dm3×0.70moldm3=1.75mol

And thus [NaCl] = 0.45mol+1.75mol4.0dm3

= 0.55moldm3.

Note that 1dm3 = (101m)3 = 103m3=1L. We have (reasonably) assumed the volumes of solution to be additive.