Milliequivalents Calculations Question from Viewer

So I received an interesting Milliequivalents calculation question from one of our viewers. It occurred to me that this is a question that most of our viewers would like to know how to solve.

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The question says, how many Milliequivalents of sodium chloride are contained in 25 mL of 0.1% solution of sodium chloride in water?

So the first thing we want to do is to start off with the equation for calculating Milliequivalents. And the equation states Milliequivalents is equal to the weight of substance in milligrams, divided by the molecular weight, times valence.

And so the first thing we can do is to determine what the valence is going to be. We have sodium chloride, which is NaCL. When you put that in an aqueous environment, it's going to dissociate into a sodium cation and a chloride anion. The valence is the absolute charge on either of the ions.

So if we use the sodium chloride ion, then it will be the absolute of positive 1, which will be 1.

Or if we chose to use the chloride ion, it's going to be equal to the absolute of negative 1, which is still one.

And so the valence of the compound is 1.

Now, the next thing that we need is a molecular weight of sodium chloride, and the molecular weight is actually 58.44 g/mol.

Now, we have the valence and we have the molecular weight. The next thing that we need is the weight of the substance in milligrams. That would be the weight of sodium chloride in milligrams.

Now, to do that, we make use of the 0.1% and the volume of the preparation.

So what that would look like is you have 0.1% which implies that you have 0.1 g of sodium chloride in 100 mL of solution. And we want to find out how many grams is actually present in 25 mL.

So we can go ahead and solve for X, which is our unknown. So X equals 0.1 g times 25 mL, divided by 100 mL.

And that's going to be equal to 0.025 g.

But notice that for the equation we need the quantity to be in milligrams. So we'll go ahead and convert the grams to milligrams and use the conversion factor that 1 g is equivalent to 1,000 mg.

So the grams cancel out and you end up with 25 mg.

And so, we can now substitute the weight of substance in milligrams, the valence and the molecular weight into the equation.

And that would imply that you have Milliequivalents being equal to 25 mg, which would be the weight of sodium chloride in the preparation divided by the molecular weight, which is 58.44. And we multiply that by the valence, which is 1

and that should be equal to 0.428, or approximately 0.43.

So I hope you found this tutorial useful. Thank you so much, and I will see you on the next blog.

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