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Please help, I’m stuck with the problem. Thank you in advance! Solution making S

ID: 1032056 • Letter: P

Question

Please help, I’m stuck with the problem. Thank you in advance!
Solution making Scenario 2 [Show work and explain steps for credit]: In a 8L container you have 4L of 0.186M NaOH; We need 8L of 0.2M NaOH in the same container.
If in the container, we bring it to volume with H2O first, how much NaOH(s) must we add to make the solution .02M. (Remember we brought our solution of 4L of 0.186M NaOH to volume (8L) with H2O first, so solution is now diluted further)

Please help, I’m stuck with the problem. Thank you in advance!
Solution making Scenario 2 [Show work and explain steps for credit]: In a 8L container you have 4L of 0.186M NaOH; We need 8L of 0.2M NaOH in the same container.
If in the container, we bring it to volume with H2O first, how much NaOH(s) must we add to make the solution .02M. (Remember we brought our solution of 4L of 0.186M NaOH to volume (8L) with H2O first, so solution is now diluted further)

Please help, I’m stuck with the problem. Thank you in advance!
In a 8L container you have 4L of 0.186M NaOH; We need 8L of 0.2M NaOH in the same container.
If in the container, we bring it to volume with H2O first, how much NaOH(s) must we add to make the solution .02M. (Remember we brought our solution of 4L of 0.186M NaOH to volume (8L) with H2O first, so solution is now diluted further)

Explanation / Answer

4.0 L x 0.186 mol NaOH / 1.0 L => 0.744 mol of NaOH present in container.

(If you dilute to 8.0 L, then concentration of NaOH becomes 0.744 mol / 8.0 L => 0.093 M)

If you want to make 0.2 M NaOH in same container total amount of NaOH must be = 8.0 L x 0.2 mol / 1.0 L => 1.6 mol of NaOH

But actual amount of NaOH present = 0.744 mol

Remaining amount of NaOH required = 1.6 - 0.744 => 0.856 mol

Mass of NaOH required = 0.856 mol x 40 g/mol => 34.24 g of NaOH

So if you add 34.24 g of NaOH to the 8.0 L container with diluted solution it becomes 0.2 M NaOH