The raoult’s law calculator works out vapor pressure of solution (p), mole fraction of solvent (x) and placeholder var from moles of solute (n₁), moles of solvent (n₂), partial pressure of solvent (pº), units var chart and one way. Enter what you have and the relationship is applied straight away, so you get the answer without working through the algebra yourself.
What Is the Raoult's Law Calculator?
The raoult's law calculator turns moles of solute (n₁), moles of solvent (n₂), partial pressure of solvent (pº), units var chart and one way into vapor pressure of solution (p), mole fraction of solvent (x) and placeholder var.
It is a quick way to get from the numbers you have to the number you need, without setting up a spreadsheet or reaching for a formula.
How the Raoult's Law Works
Each result follows from the ones before it, and the calculator shows every step, so a surprising answer can be traced back to the input that caused it.
Round your inputs to the precision you actually know, and keep more precision than that in the intermediate steps.
Getting a Result You Can Trust
Run the calculation twice with slightly different inputs. A sensible calculator moves its output in proportion; a wild change points to a unit or a decimal point problem in what you entered.
Write the inputs down next to the answer. It takes a moment and it is the difference between a number you can explain and one you cannot.
A Worked Example
Working through an example, with moles of solute (n₁) set to 10, moles of solvent (n₂) set to 5, partial pressure of solvent (pº) set to 2, the calculator returns vapor pressure of solution (p) of 1.33, and mole fraction of solvent (x) of 0.67, and placeholder var of 100. Substitute your own figures and the same steps produce the same kind of answer.
Frequently Asked Questions
What do I need to work out vapor pressure of solution (p)?
Enter moles of solute (n₁), moles of solvent (n₂), partial pressure of solvent (pº), units var chart and one way. The calculator then works through the relationship and reports vapor pressure of solution (p), mole fraction of solvent (x) and placeholder var.
What does the raoult's law actually calculate?
It takes moles of solute (n₁), moles of solvent (n₂), partial pressure of solvent (pº), units var chart and one way and converts them into vapor pressure of solution (p), mole fraction of solvent (x) and placeholder var using the standard relationship for this problem. Each step is applied in turn, so every output is traceable back to the numbers you typed in.
How should I enter moles of solute (n₁)?
Use the value you actually have, in the unit shown next to the field. Enter every value in the same unit system. The calculator assumes the figures you supply are consistent, so it cannot correct a mistake that happens before the calculation starts.
Why does a small change in one value move the answer so much?
That happens when an output depends on a ratio, because dividing by a small number magnifies any change in it. Check the units first, then check whether the value you entered is in the range the relationship was designed for.
Is the answer exact?
It is as exact as the formula and the inputs allow. The method itself is the standard one for this problem, so the only sources of error are the figures you enter and the precision you ask for.