1
$\begingroup$

I found this formula for calculating the Normality from the Molarity: $$\text{Normality} = n \cdot \text{Molarity}$$

with $$n = \frac{\text{Molecular weight}}{\text{Equivalent weight}}$$

But in one book I found that if Equivalent weight is equal to half of Molecular weight then $$2N = M$$

In this condition I am confused if this statement true.

Am I following correct book for solving problem of Volumetric Analysis?

$\endgroup$
2
$\begingroup$

The normality of a solution is the molarity of the solution multiplied by the number of equivalents per mole:

$$\mathrm{N} = \mathrm{{eq\over mol}}\cdot\mathrm{M}= \mathrm{{eq\over mol}}\cdot\mathrm{{mol\over L}}=\mathrm{{eq\over L}}$$

Example: Calculate the normality of a 1 $\mathrm{M}$ solution of $\ce{H2SO4}$. There are 2 equivalents per mole, from the reaction

$$\ce{H2SO4 -> 2H+ + SO4^{2-}}$$

which yields 2 moles of $\ce{H+}$ for every 1 mole of $\ce{H2SO4}$.

Using the relation given above, we find that a 1 $\mathrm{M}$ solution of $\ce{H2SO4}$ is 2 $\mathrm{N}$:

$$\mathrm{{2\;eq\over mol}}\cdot\mathrm{1\;M}=2\;\mathrm{N}$$

One resource you might find useful in order to check your math is Sigma-Aldrich's Normality & Molarity Calculator. Additionally, there are details relevant to the definitions of molarity and normality that you might find clearer that the ones you've conveyed in your question.

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.