Molality is depicted as moles of solute per kilograms of solvent. Molality, which is lowercase m, here we have moles of our solute, which is a smaller part of our solution, divided by kilograms of the solvent, the larger portion of our solution. Now, this is similar to molarity, which has capital M. It too has moles of solute as the numerator, but the denominator is actually liters of solution. Because of their similarities, there are questions which at times will ask you to interchange between the two. Now, in the same way we can expand molarity, the same approach can be applied to molality.

So let's say that we have 0.30 moles of sodium chloride. What does this translate into? Well, this just means that we have 0.30 moles of the solute, which is sodium chloride, divided by 1 kg of our solvent, which is usually water. Let's say for example that we had 0.25 M of glucose in an aqueous solution. Now, again, 0.25 M. The number itself means that's how many moles we have of the solute. So, it'd be 0.25 moles of glucose. Here we say aqueous solution. Aqueous means that our solvent is water so that would be 1 kg of water.

So the takeaway from this is, remember, if they give you molality of a compound or solution, it just means that number in terms of moles divided by 1 kg of our solvent. This will be important to remember if we're trying to convert molality to let's say molarity or mole fraction or even mass percent. Now that we've learned the basics of molality, click on to the next video and take a look at "Molality".