How to calculate weight needed for a concentration

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Discussion Overview

The discussion centers around calculating the amount of resveratrol needed to achieve a specific concentration (5 uM) in a solution of dimethylsulfoxide (DMSO). Participants explore the definitions and calculations related to molar concentration, particularly in the context of chemistry and solution preparation.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • One participant seeks to determine how much resveratrol to add to 10 grams of DMSO to achieve a 5 uM concentration.
  • Another participant emphasizes the need to clarify the unit "5 uMol," suggesting it likely refers to micromoles.
  • A participant provides a formula for calculating the required grams of resveratrol, noting the importance of including density and proper units in the calculations.
  • Concerns are raised about the safe handling of DMSO, including storage and exposure considerations.
  • There is a clarification regarding the density of DMSO, with one participant correcting the molar mass and density values provided earlier.

Areas of Agreement / Disagreement

Participants generally agree on the need for clarity regarding units and the calculation process, but there are differing views on the correct interpretation of the density and molar mass of DMSO, as well as safety considerations when handling it.

Contextual Notes

Participants mention the importance of looking up the density of DMSO and the potential confusion surrounding the terminology used for concentration units. There are unresolved aspects regarding the exact values needed for calculations and safety protocols.

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Please post this type of questions in HW section using the template and showing your work.
I haven't had a chemistry class in many years. Recently I saw an interesting article that used a solution of resveratrol (228.25 grams per mole) in dimethylsulfoxide (78.13 grams per mole). The concentration was listed as 5 uMol.
If I had 10 grams of DMSO how much resveratrol would I add to achieve the 5 uMol concentration? And how is this calculated? Thanks.
 
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Start with the definition of molar concentration.
 
Would you be clearer about the "5 uMoL" ? What is that unit? Micro-something. Either you mean, MOLES, MICROMOLES, MICROMOLES-or-LITER, MICROMOLES PER LITER,... What?
 
Borek said:
M usually stands for mol/L, mM and μM are rather common and unambiguous extensions. What is a bit confusing is your way of calling it μMol.
Okay, micromoles per liter.
You want 5 micromoles per liter of resveratrol. You 'have' 10 GRAMS of DMSO and you wish to find how much resveratrol is needed.

Use x grams of resveratrol,
d is density of dimethylsulfoxide as grams per milliliter , which you need to look-up,
and you should fill in the unstated units of measure to be sure you see the way the two numbers work,
and the right side is as MOLES per LITER:
(x(1/228.25))/(10*(1/d)*(1/1000))=0.000005

(Micro moles per liter, the same as the number shown on the right side)
That is in plain text but you could rewrite in normal notation on paper, yourself so more understandable.
Solve for x.

Note: the density of DMSO is NOT 78.13 grams per mole and not moles per liter. See a handbook.

Also, note, https://en.wikipedia.org/wiki/Resveratrol
 
Last edited:
I'd guess that a person should not go playing with dimethylsulfoxide without care and knowledge. Storage? Exposure? Grades of quality? Material Safety Data Sheet?
 
https://en.wikipedia.org/wiki/Dimethyl_sulfoxide
According to Wiki, the density is almost like water at 1.1004 g cm−3.
78.13 is the molar mass, which I thought might have been needed.
Thanks for the formula. I will rearrange it on paper when I get a chance.
Also good to know was that uM means micro-moles per liter. Would not have guessed that.
 

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