# Chemistry

posted by .

Imagine that you have been asked to prepare 500ml of a 0.25 mol L solution of Sodium Hydroxide, NaOH. Describe how you would prepare this solution. Include any calculations that you would perform.

chemistry - DrBob222, Thursday, October 14, 2010 at 9:00pm
I assume you meant 0.25 moles/L.
M = moles/L
0.25 = moles/0.500 L
moles = 0.125 moles.
Then moles = grams/molar mass
molar mass NaoH = 40 g/mole
grams = 0.125 x 40 = ??

So you want to place ?? g NaoH in a 500 mL volumetric flask, dissolve in some water, then make to the mark with distilled water.

chemistry - Dexter, Friday, October 15, 2010 at 7:34pm
amazing help - this is what I got too however they also want me to explain the steps I would take to prepare this solution. I'm using a graduated cylinder to measure the sodium hydroxide and need to convert the 5 grams to ml. I'm not sure the steps to take. Do I use the molar concentration formula with Vi x 0.125 mol/L = .500L x 0.25 mol/L ? Doing this doesn't seem right to me because I get the answer 1 L. Please let me know. Thank you so much for your help, it really was appreciated and helped me verify my work.

• Chemistry -

See my response above.
Now that I read this part, I'm convinced you are NOT familiar with the volumetric flask and perhaps not with NaOH. I'll start over here.
You want to weigh 5.00 grams NaOH (0.125 x 40 g NaOH/mol NaOH = 5.00 g NaOH) on a balance (triple beam or whatever you are using in the lab --not an analytical balance I wouldn't think since NaOH is so corrosive), place the solid NaOH into a 500 mL volumetric flask, add a little water, swirl until all of the NaOH is dissolved, the add water to the mark of the flask (the mark is located on the neck of the flask). Then pop in the stopper (usually these are ground glass fittings), mix the contents thoroughly and you will have 500 mL of a 0.25 M solution of NaOH (if the NaOH were absolutely pure). Technically, no one ever makes NaOH this way because it isn't pure enough as it comes out of the bottle to make it EXACTLY 0.25 but it would be close. In the real world, we weigh the solid NaOH on a triple beam balance, go through the process outlined above, and that makes a solution that is VERY CLOSE to, but not exactly, 0.25. THEN we use an acid with a known molarity (exactly) and titrate the acid against the base and calibrate the NaOH that way.

• Chemistry -

I got lost in all the material I'm learning which is why I posted here. Thank you for helping me sort all this out. I was looking at the problem all wrong thinking that the NaOH was a liquid. Very new to chemistry...slowly but surely getting it, thanks for your help, it made a difference!

• Chemistry -

You're quite welcome. Come back anytime. We like for you to show what you can do on your on, then explain what you don't understand about the next step.

## Similar Questions

1. ### BIOLOGY

Relate the classification of an organism to its phylogeny Please read the following page: (Broken Link Removed) Thanks for the website Lance. However, i cant really find the answer to my question in there. can you help please?
2. ### Math

I have a question I am having a hard time with..... 2 more than 6 times a number divided 3 Would this be read as (6p / 3) + 2 or 6 (p/3) + 2 thank you for your help!!! Both are correct. In the second one, 6 is equal to 6/1, so when …
3. ### english

in English class, we have been studying The Odessy. In the portion of Scylla and Charybdis, we have been recognizing strong body, strong intellect, episodes, etc... the one thing I need that I cannot uncover is whether or not there …
4. ### PSY 240

What is the difference between the idea of set points versus settling points in relation to weight control?
5. ### chemistry

Imagine that you have been asked to prepare 500ml of a 0.25 mol L solution of Sodium Hydroxide, NaOH. Describe how you would prepare this solution. Include any calculations that you would perform.
6. ### Chemistry

Please read to the bottom - This help was wonderful and absolutely correct, I'm asking a bit more regarding the same question, please read below. Imagine that you have been asked to prepare 500ml of a 0.25 mol L solution of Sodium …
7. ### Psychology

Please help! I have read and read and still don't no for sure if this is the correct answer to this question. I picked A, but leaning more toward D Which approach would explain that phobias are acquired through classical conditioning …
8. ### SS7R - Corrects!

1. DR 2. F 3. F 4. DR 5. DR ~~~~~~~~~~~~~~~~~~~~~ 6. F 7. DR 8. DR 9. DR 10. F Read my last post below (Social Studies 7R - Please Read!). Are these are correct?
9. ### 3 grade math ms sue

use tools 1-when using fraction strips, how do you know that two fractions are equivalent?
10. ### English

Identify the sentence for questions 16-18 that contains NO errors in punctuation or use of italics. 16. A.) Catherine asked, "Where are you going"?

More Similar Questions