Question #a939a

1 Answer
May 20, 2017

Answer:

#"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.