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/sci/ - Science & Math

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2465454 No.2465454 [Reply] [Original]

Hey /sci/, am I doing this correctly?

"You will prepare 1-liter of approximately 0.15M sodium hydroxide solution by diluting a commercial stock solution that is 50% NaOH by mass and has a density of 1.525g/mL.

First, calculate the number of grams of NaOH required to make one liter of a 0.15 M NaOH solution, then calculate the number of grams of a 50% solution of NaOH, and lastly use the density to determine the volume of this solution required."

So I started by finding out how many moles is in 0.15M and I guess it would also be .15 mol since it's in 1 liter anyway. Then to get grams I'd multiply by the molar mass of 39.99 to get 5.99g. Multiply by 2 since it's 50% by mass (if I understand what this means correctly) to get 11.99g, then divide by the density it gave to figure out how many mL to add. I got 7.86 or so.

Right?

>> No.2465592

Bump.

>> No.2465600

OK, first step, find the M in solution
Post when you're done

>> No.2465601

.pmuB

>> No.2465612

>>2465600
Sorry
The M of NaOH in stock

>> No.2465633

>>2465600
Not what he asked.

>> No.2465642

>>2465633
It's the first step to being right

>> No.2465677

>>2465612
How would you do that since the volume of the stock solution seems arbitrary in this case?

M = mol/L

>> No.2465679

.3L

>> No.2465695

>>2465677
>50% NaOH by mass and has a density of 1.525g/mL.

>> No.2465717

Going to sleep, fast response there OP

>> No.2465727

I'M WORKIN ON IT.

Making sure I understand this correctly.

>> No.2465843

Huh. I get the same answer, 7.867mL, if I do it by finding M of NaOH first as my original method.