Question

Question #a939a

Answer 1

`"26% NaCl"`

Explanation:

The problem wants you to calculate the percent concentration by mass, `"% m/m"`, of sodium chloride in this solution.

The key thing to remember here is that a solution's percent concentration by mass tells you the mass of solute, which in your case is sodium chloride, present for every `"100 g"` of solution.

After you dissolve the sodium chloride, the mass of the solution will be

`m_"solution" = "36 g" + "100 g" = "136 g"`

You know that you have `"36 g"` of sodium chloride in `"136 g"`, so use this as a conversion factor to find the mass of sodium chloride present in `"100 g"` of solution

`100 color(red)(cancel(color(black)("g solution"))) * "36 g NaCl"/(136color(red)(cancel(color(black)("g solution")))) = "26.47 g NaCl"`

This means that the solution's percent concentration by mass is

`color(darkgreen)(ul(color(black)("% NaCl" = 26%)))`

The answer is rounded to two sig figs.