Question #608c2
1 Answer
Explanation:
As you know, a solution's percent concentration by mass tells you the number of grams of solute present for every
In your case, the solution is said to be
Consequently, this
#"mass of solvent" = overbrace("100 g")^(color(blue)("mass of solution")) - overbrace("3.22 g")^(color(blue)("mass of solute"))#
#"mass of solvent = 96.78 g"#
of water, the solvent. Now, in order to find the molality of the solution, you need to figure out how many moles of sodium nitrate are present for every
Since you know how many grams of sodium nitrate are present for every
#10^3 color(red)(cancel(color(black)("g water"))) * "3.22 g NaNO"_3/(96.78color(red)(cancel(color(black)("g water")))) = "33.27 g"#
then use the molar mass of sodium nitrate to convert the number of grams to moles.
#33.27 color(red)(cancel(color(black)("g"))) * "1 mole NaNO"_3/(84.9947color(red)(cancel(color(black)("g")))) = "0.391 moles NaNO"_3#
You can thus say that the molality of the solution, i.e. the number of moles of sodium nitrate present for every
#color(darkgreen)(ul(color(black)("molality = 0.391 mol kg"^(-1))))#
The answer is rounded to three sig figs, the number of sig figs you have for the percent concentration of the solution.