Can you help me with this? 20 g of glucose is dissolved in 150 g of water. Calculate the molarity, molality & mole fraction of glucose in solution.
Here's how you can go about solving this one.
The problem gives you all the information you need in order to solve for the molality and mole fraction of the solution. In order to determine its molarity, you're going to need the solution's volume.
In your case, the mass of the solution will be
This means that you get
The density of this solution will thus be
Use glucose's molar mass to determine how many moles you have
The solution's volume will be
This means that its molarity is - do not forget to convert the volume to liters!
To get the mole fraction of sucrose, you need to know how many moles of water you have present. Once again, use water's molar mass
The total number of moles the solution contains is
This means that the mole fraction of sucrose, which is defined as the number of moles of sucrose divided by the total number of moles in the solution, will be
SIDE NOTE I've left the values rounded to two sig figs, despite the fact that you only gave one sig fig for the mass of glucose.