Question

In order to make a `1*mol*L^-1` solution of `NaNO_2` in water, how many grams of sodium nitrite are necessary?

Answer 1

Concentration `=` `("moles")/("volume of solution")`. Here you need a `1` `mol*L^-1` solution.

Explanation:

We require, `(5*mmol)/(5*mL)` `=` `(5xx10^(-3)*mol)/(5xx10^-3*L)` `=` `1` `mol` `L^-1`

Note that the `m` prefix simply means `xx10^-3`. So `mmol*mL^-1` is precisely `1` `mol*L^-1`.

So to make this volume we simply take a `5` `mL` volume of `1` `mol*L^-1` sodium nitrite.

It would be best to make a stock solution. Accurately weigh `70.00` `g` of sodium nitrite, and quantitatively transfer this to a `1` `L` volumetric flask. Fill up to the mark with distilled water, and make sure all the solid is dissolved.