Question

How many moles of each element are present in 1.000L of a 0.295 M solution of sodium chloride?

Answer 1

`0.295`.

Explanation:

You know that molarity is defined as the number of moles of solute present in exactly `"1 L"` of a solution.

Basically, what this means is that if you know the molarity of a solution, you know how many moles of solute are present for every `"1 L"` of that solution.

In your case, you're dealing with a `"0.295-M"` solution of sodium chloride, so right from the start, you can say that this solution will contain `0.295` moles of sodium chloride, the solute, for every `"1 L"` of the solution.

So in your `"1.000-L"` sample of this solution, you will have `0.295` moles of sodium chloride.

Now, sodium chloride is soluble in water, which implies that it exists as ions in aqueous solution.

`"NaCl"_ ((aq)) -> "Na"_ ((aq))^(+) + "Cl"_ ((aq))^(-)`

So for every mole of sodium chloride that you dissolve in water to make your solution, you will end up with `1` mole of sodium cations, `"Na"^(+)`, and `1` mole of chloride anions, `"Cl"^(-)`.

This means that your `"1.000-L"` sample contains `0.295` moles of sodium cations and `0.295` moles of chloride anions.

If you want the number of moles of each element, you can say that the `0.295` moles of sodium cations correspond to `0.295` moles of sodium, the parent element of the cation and that the `0.295` moles of chloride anions correspond to `0.295` moles of chlorine, the parent element of the anion.