Question

Question #cd3c6

Answer 1

It will be a `.1 " M"` solution of both `Na^+` and `Cl^-` ions.

Explanation:

By salt, I assume you mean common table salt, `NaCl`. You are given that you have .2 moles of salt, thus you have #.2" mol " Na^+ "and " .2 " mol " Cl^-#.

Molarity is defined as the moles of a substance per Liter, so the molarity of the solution for both `Na^+` and `Cl^-` is as follows:

`(.2" moles")/(2" Liters") = .1 ("mol")/("Liter") = .1 " M"`

Answer 2

`"0.1 mol L"^(-1)`

Explanation:

All you need to know here is that molarity is defined as the number of moles of solute present for every `"1 L"` of the solution.

This means that in order to find the molarity of a given solution, you must determine how many moles of solute are present for every `"1 L"` of this solution.

In your case, you know that `0.2` moles of solute are dissolved in `"2 L"` of the solution. Your goal here is to figure out how many moles of solute must be present in `"1 L"` of this solution in order to have a solution of equal concentration to the one that contains `0.2` moles of solute in `"2 L"` of the solution.

`"? moles solute"/"1 L solution" = "0.2 moles solute"/"2 L solution"`

Rearrange to get

`? = (1 color(red)(cancel(color(black)("L solution"))))/(2color(red)(cancel(color(black)("L solution")))) * "0.2 moles solute"`

`? = color(darkgreen)(ul(color(black)("0.1 moles solute")))`

The answer is rounded to one significant figure.

So, you can say that this solution will have a molarity of `"0.1 mol L"^(-1)`, which implies that `"1 L"` of the solution will contain `0.1` moles of solute.

Answer 3

The molarity of the salt solution is `"0.1 M"`.

Explanation:

`"molarity"=("moles of solute")/("1 L of solution")`

There are `"0.2 mol of salt"` dissolved in `"2 liter of salt solution"`.

`"molarity"=("0.2 mol salt")/("2 L")="0.1 mol salt/L = 0.1 M salt"`