Question #7deb5
1 Answer
The answer is (c)
Explanation:
Molality is simply a measure of the number of moles of solute present for every
This means that a
#"1 molal " implies " 1 mole glucose" color(white)(.)color(blue)("for every")color(white)(.)"1 kg water"#
As you know, you have
#"1 kg" = 10^3# #"g"#
This means that your solution will contain
#"1 molal " implies " 1 mole glucose" color(white)(.)color(blue)("for every")color(white)(.)10^3color(white)(.)"g water"#
Now, the mass of a solution is always equal to
#"mass solution = mass solute + mass solvent"#
This means that the mass of a
#"mass 1-molal solution" = "mass of 1 mole glucose" + 10^3color(white)(.)"g"#
To find the mass of
#1 color(red)(cancel(color(black)("mole glucose"))) * "180.156 g"/(1color(red)(cancel(color(black)("mole glucose")))) = "180.156 g"#
This means that the mass of above solution will be
#"mass 1-molal solution" = "180.156 g" + 10^3color(white)(.)"g"#
#"mass 1-molal solution = 1180.156 g"#
Now, you need your target solution to contain
#"0.2 moles glucose" = "1 mole glucose"/color(red)(5)#
Since solutions are homogeneous mixtures, i.e. they have the same composition throughout, you can say that the mass of solution that will contain
#"mass solution" = "1180.156 g"/color(red)(5) ~~ color(darkgreen)(ul(color(black)("236 g")))#