[TahaCRS]

Hi all,

I got this assignment from my teacher to prepare for a small research project. However, I have no idea what I'm supposed to do (her teaching isn't the greatest) and how to continue from here. My buddy did the first 3 assignments and I'm left with these 3:

• Calculate how much gram sodium thiosulfate has to be resolved in a 1000 mL flask to create a 0,0100 M solution.
• Calculate the molarity of hydrogen peroxide in a solution that has 6 volumepercent hydrogen peroxide. The density of a hydrogen peroxide-solution is 0,998∙10³ kg m^–3.
• At a titration we want the cage usage to lay between 10 and 25 mL. Calculate if the hydrogen peroxide-solution (6%) has to be diluted. If yes, how much times?

I translated these assignments myself so if there's anything unclear please tell me and I'll do my best to fix it. Thanks in advance.

[Arkcon]

Welcome, TahaCRS: to the Chemical Forums.  According to the Forum Rules{click}, we want to see your attempt.  This is sometimes a problem for new users, who sometimes believe translating, posting, and their next steps is enough work.

Let's start with your first problems.  You did post three you notice.  You can use the answer to the first one to help you with the next.  You're given grams, and you're asked to make a M solution.  What is the definition of M?  Can you use that to figure out what to do?

[TahaCRS]

Not so sure how to even begin. Like I said, my teacher doesn't get the best results out of me nor my other classmates. I had the 'luck' to receive the 3 hardest questions of the whole project. I know that M stands for molarity/molar concentration and I tried to Google a few formulas to convert everything but none of them are applicable to my problem.

This is the furthest I got:

mol/liters = molarity > 0,0100/1 = 0,0100 mol/liter
0,0100 * 1000 = 10 grams

I know for a fact that this is completely wrong but I couldn't find any other formula to work with.

[Arkcon]

Well, let's try to piece the knowledge you need out, a little bit at a time.  Suppose you need to make a 1 M solution.  What would that mean?  You can quickly determine what you'd need to do, to make a 0.1, or a 0.01 M solution (which is what you need) once you know how to make a 1 M solution.  Warning, its not 10 grams.  How did you get that?  Grams doesn't appear anywhere, in the definition of molarity.  Look up the definition in your textbook, save Google for when you have a fair idea of what's going on.

[TahaCRS]

Still don't understand. I'm not a chemist by any means. I'm not even going to pursue chemistry but I have to hand this assignment in in a couple of hours so I just came here for a quick explanation but I can't put too much time in it. I'll see if I can Google some more formulas to go along with the problems which will hopefully get me my desired outcome.

[Borek]

What does it mean "1 M" solution? What is the definition of molar concentration?

http://www.chembuddy.com/?left=concentration&right=molarity