Question #5d96e

1 Answer
Aug 24, 2015

Molarity: #"0.0834 M"#


The molarity of a solution is defined as the number of moles of solute divided by the number of liters of solution.

#color(blue)(C = n/V)#

This means that in order to find a solution's molarity, you need to know two things

  • the number of moles of solute;
  • the volume of the solution

You know that the volume of the solution is exactly one liter, so you only need to work out how many moles of #"KHP"# you get in that many grams of the compound.

To do that, you need to use potassium hydrogen phthalate's molar mass, which will tell you what the mass of one mole of #"KHP"# is.

If you look up this value, you will get that potassium hydrogen phthalate has a molar mass of 204.22 g/mol. This means that every mole of potassium hydrogen phthalate has a mass of 204.22 g.

You have a much smaller mass available, so will of course get less than one mole of #"KHP"# in your solution. More specifically, you have

#1.43color(red)(cancel(color(black)("g"))) * "1 mole KHP"/(204.22color(red)(cancel(color(black)("g")))) = "0.0834 moles KHP"#

This means that the molarity of the solution will be

#C = n/V#

#C = "0.0834 moles"/"1 L" = color(green)("0.0834 M")#

If you take into account the number of sig figs you gave for the volume of the solution, the answer should be rounded to one sig fig

#C = "0.08 M"#