which solutions have concentrations of 0.1, 0.2, 0.3 and 0.4 mol/dm3?
1) 50 ml NaCl solution.
2) 40 ml NaCl sol. and 10 ml water.
3) 30 ml NaCl sol. and 20 ml water.
4) 25 ml NaCl sol. and 25 ml water.

Also, how do I go about calculating the concentrations?
Thanks in advance!

Question

which solutions have concentrations of 0.1, 0.2, 0.3 and 0.4 mol/dm3?
1) 50 ml NaCl solution.
2) 40 ml NaCl sol. and 10 ml water.
3) 30 ml NaCl sol. and 20 ml water.
4) 25 ml NaCl sol. and 25 ml water.

Also, how do I go about calculating the concentrations?
Thanks in advance!

aaronq · Answer

we'll you just have to take into account the volume of water added. The most concentrated doesnt have any water added, the least has the most water added.

anonymous · Answer

Got it. Thanks. By the way, i forgot to mention that 200 g of NaCl was added to 600 ml water. So, how do I find the conc. for each solution? p.s forget I mentioned the concentrations before. It's actually a biology lab where I had to prepare solutions of different concentrations. Since the concentration now would be 5.7 mol dm^-3, right?

aaronq · Answer

mol/dm^3 = Molarity

$Molarity=\dfrac{n_{solute}}{L_{solution}}=\dfrac{m}{M_r*L_{solution}}$

Mr is molar mass

aaronq · Answer

that's to find the initial concentration. then it's just a dilution:  $M_1V_1=M_2V_2$

anonymous · Answer

Thank you so much!