Which is greater molarity or molality

If you're seeing this message, it means we're having trouble loading external resources on our website. To log in and use all the features of Khan Academy, please enable JavaScript in your browser. Donate Login Sign up Search for courses, skills, and videos. Molarity vs. Practice: Molarity calculations. Current timeTotal duration Google Classroom Facebook Twitter. Video transcript Let's talk about the difference between two words molarity and molality.

So the first one has obviously, a little r in it, and the other has an l in it. And in fact, sometimes when people say it quickly, it's hard to even hear which one they just said, so just make sure you listen carefully because there is a slight difference, actually, two little differences that we'll talk about. So molarity, let's start there, is really talking about moles of something, some particle, over 1 liter of solution. And I haven't been writing out liter of solution, but that is what is meant, so one liter of solution, that is molarity.

Now, molality is slightly different, so let me do it in a different color. Molality is actually the moles, again-- so that part is the same-- over 1 kilogram-- so this is now actually looking at mass-- 1 kilogram of solvent, so not solution, but solvent.

And so let me make that very clear. So this is 1 liter of solution. This is 1 kilogram of solvent. So both are looking at the same numerator, but the denominator is different. So let me actually draw out an example of what this might look like. Let's say we have our solution down here, and let's say it's mostly water, so I'm going to fill this in with water, and let's fill it in more quickly using a little air brush.

So let's say this is our solution of water. I'm going to make it nice and even. You can see the line that it goes up to. So this is carefully measured out, and I'm going to put 1 mole of something, and we can decide whatever that something is going to be. And in this case, I don't know, let's say we decide to put some urea in there, little molecules of urea.

And we know the urea is something our body uses to get rid of nitrogen, so something that we throw into urine and actually even sounds like urine. Ask Question. Asked 6 years, 8 months ago. Active 4 years, 8 months ago. Viewed 13k times. My approach is: Convert 1M into molality and then compare if it is less or more than 1m. The density of water is 1kg per L.

When solute is added to it, density would definitely increase? And therefore 1L of that solution will weigh more than 1 kg. Density would always? Improve this question. Curt F. Let me know if I've altered your meaning in any way. Add a comment. Active Oldest Votes.

The factor of is because molality is moles per kg of solvent, not moles per g. Good approach. Not necessarily true. Improve this answer. Please check your email for login details. Studying in Grade 6th to 12th? Registration done! Sit and relax as our customer representative will contact you within 1 business day Continue. Forum Physical Chemistry which is greater molality or molarity? Enter email id Enter mobile number. Cancel Notify me. Indu 47 Points. Other Related Questions on Physical Chemistry.