How to make 1 mM and 100 mg/L solution of Salicylic acid

Answer 1

Hello, Ali,

[Note: Zachary M. noted that my initial answer did not correctly transfer the 0.001 molar to the actual calculation. I've corrected that with this update.]

I'll assume that "1 mM" means 1 millimolar.

Milli- is the metric prefix for 1/1000, or 0.001. So 1 mM would be 0.001 Molar. Molar is defined as moles/liter. Since we are not told how MUCH of the solution is needed, I'll assume a convenient value of 1 liter. This would mean to get a 1mM solution, we need to add 0.001 moles of salicylic acid to 1 liter of solution.

To find out how many grams that is needed, find the molar mass of salicylic acid, which I calculate to be 138.1 g/mole, based on its chemical formula: C₇H₆O₃.

To find grams, multiply the moles needed (0.001 moles) by the molar mass, to arrive at 0.138 grams of salicylic acid. Add that amount to one liter of solution and you'll have a 1mM solution of salicylic acid.

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The 100mg/Liter question seems too obvious, but I'll go for it: Dissolve 100 mg of salicylic acid into 1 liter of solution.

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I hope this helps,

Bob