Lab Skills: Preparing Stock Solutions

[@angielane01]

Thank you. That was SUPER helpful! I start my new job in a research lab tomorrow. :)

[@ItsLearnable]

Best of luck!

[@angielane01]

@@ItsLearnable Thank you! It is going really well.

[@sabirazahoor5468]

Thank you so much. It helped me a lot ☺

[@ItsLearnable]

👍

[@haider677]

You can actually calculate the molecular weight, for example: Nacl: Atomic mass of (Na = 22.98 u ) and (Cl = 35.5 u) which is on the periodic table or is generally the double of atomic num (Atomic number of Na = 11 and Cl = 17) so by adding atomic masses (NaCl = 22.98 + 35.5 = 58.48 g/mol)

[@ItsLearnable]

That's true, but not all reagents in the lab can be calculated in this way. Some compounds may have some H2O molecules associated with them even in the "pure" form that you receive from the supplier. This affects the formula weight of the compound and will cause your calculations to be inaccurate if you just rely on using the periodic table. It is always a good idea to check the reagent bottles in your lab for the formula weight - just to make sure your calculations are correct before weighing anything out.

[@goldlaboratory256]

How do you prepare standard solutions for calibration of the AAS. FOR EXAMPLE: 0.2ug/l, 0.3ug/L, 0.5ug/L 0.5ug/L, 0.6ug/L

[@ItsLearnable]

Making of any standard series like that, would involve making a stock solution at a relatively high conc. (ie. 1ug/L or 2ug/L), and then using it to make serial dilutions to get the other standards.

[@artantahiri1977]

isopropyl alcohol 99.9 is this product same as ssd solution is it with same purposes that can be usdd to clesn etc

[@ItsLearnable]

Do you mean SDS? No it's not the same.

[@bellabconcept1432]

How many gram of K2Cr2O7 does it require to produce 0.1N of the compound

[@Time2ChooseYou]

If 50mL of our stock was created initially, why did we add water as the remaining 50mL to top up to 100mL? Or was did this second 50mL also contain 5.84g of NaCl?

[@ItsLearnable]

Please keep in mind that this video is meant as a general protocol for making just about any solution - not just a 1M NaCl solution. I this case, I added 50ml of water at the end because the calculations were made for 100ml. So, if I didn't add the 50ml, my concentration would actually be 2x as high as it should be. I ask students to start with about half the volume, when learning to make solutions, because I want them to develop that habit. Sometimes, when making solutions, you need to adjust the pH. In those cases, the act of adding acid or base, will change the volume, so you need to make sure you leave "room" for that. By developing the habit of starting with a lower volume, you avoid the problem of overshooting the total volume in solutions you need to pH.

[@susmitasarkar6423]

Thank you sir ,🙏

[@ItsLearnable]

Most welcome

[@scottagyekum7669]

Thank you very much, Sir. Please how many grams of Ni should I use to prepare Nickel Chloride stock solution using 500ml and 1000ppm?

[@ItsLearnable]

Calculating PPM solutions is a little different, and I don't often see it in Biology labs, hence I don't have any videos on this. But questions like this have been answered in many other places. Here's an example: www.quora.com/Whats-the-procedure-to-prepare-1000-ppm-Na-solution-using-NaCl

[@artantahiri1977]

i will use it for papers and do you have chemical for any kind of color that i can remove colors from papers with your chemical

[@ItsLearnable]

I'm not quite sure what you're asking for. This is just a video showing how to make solutions in general.

[@Khin-Jay]

Thanks very much At least i have learnt on how to handle every equipment in a lab

[@ItsLearnable]

Great to hear!

[@sakariasakaria6364]

GRAT , REALLY HELPED

[@ItsLearnable]

I'm glad it did.

[@bellabconcept1432]

It really helped Please, can you make a video on Normality preparation. This video is For Molarity only

[@ItsLearnable]

Hi, sorry for the late reply. This video goes over the general protocol for making a solution. It doesn't really focus on the calculations that much. I don't currently have a video on calculating normal solutions (partially because I see Molar solutions used far more commonly in a molecular biology lab), but this site explains it fairly well: www.labce.com/spg931723_what_is_a_normal_solution.aspx

[@miumihp374]

THANK YOU

[@ItsLearnable]

You are welcome. I'm glad you found it helpful

[@emiljivishov5031]

Aren't graduated cylinders for dispensing the solvent only, like a "bigger graduated pipette"? I believe using volumetric flask instead of the graduated cylinder will serve the purpose better. You may compare the error amounts on the gr. cylinder and vol.flask and will see that the latter has lower error amount, therefore is the preferred glassware to prepare stock solutions. And it has a stopper for mixing and storing :) And you don't need to worry about it leaking... :) For example: kzbin.info/www/bejne/nqPZiaiOZbSqadU

[@ItsLearnable]

Graduated cylinders work just fine for what we need. What you suggest may be more common in a chemistry laboratory, but I've never used volumetric flasks in molecular biology labs. It's likely just a case of domain-specific preference.

[@emiljivishov5031]

​​@@ItsLearnablePlease don't take it wrong, but if a glassware contains a beak, then it is used for measuring and dispensing liquids, not preparing solutions by torturing yourself with preventing leakage while mixing. "We always have done it like this" is a dangerous approach in science. Good luck!

[@TheAwesomedude4u]

🙏🏼💯

[@ItsLearnable]

👍