@pkaps01 couple of thoughts: correct me if I’m wrong but the KA video you linked is outside of the MCAT-centric videos. Additionally, Kaplan does not define osmolarity in the given example, it’s just a given variable as part of the question (fill-in-the-blank for the appropriate equation).
I agree the card needs some sprucing up, no doubt there.
For the Kaplan example I was more pointing to proof that osmolarity is a measure of concentration - “total osmolarity of 1,000 mOsm/L” - pointing to the mOsm/L aspect. and also that a grasp of osmolarity is important for solving questions involving osmotic pressure = iMRT which we also have a card for in the deck.
I couldn’t find an MCAT specific KA video for osmolarity maybe I’m missing it somewhere - this was just the video in the extra section that supports my suggestion. Kaplan also included this problem but doesn’t give the formula for calculating it. Do you see it in the UWorld textbooks?
Right up your alley:
UWorld:
- “…to the molar concentration of osmotically active solute species (ie, the osmolarity”
I think we’re pretty well good there. I’d like to clean up the Extra portion, though. Osmolarity is given by iM which I think is a good angle to specify that 1 M of NaCl will dissociate and have an osmolarity of 2, owing to the van’t Hoff factor.
It doesn’t have to be wordy, or even explain all that, but noting that 1M of NaCl, dissociating into two particles, will have an osmolarity of 2 is probably a key (and sufficient) point.
I feel this is a good space for an explanatory tone, to dodge the inherent confusion:
- 1 mol of NaCl in 1 L of water would have a molarity of 1. However, because it will dissociate into two particles (Na+ and Cl-) it will have an osmolarity of 2.
Then, if you want the extra detail, I suppose we could include the equation (it’s so short):
- Osmolarity = iM, where i is the van’t Hoff factor (number of osmotically active species) and M is molarity
Doesn’t have to be that language specifically; those are just guideline ideas for how I imagine it. I can very much see someone who is less familiar with the concept reading that Text field and being like “wtf does that mean, tho?” and so a little softening of the concept with an explanatory tone might soften the burden of confusion.
I like your wording for both of these. Edited my suggestion with them.
Hi @Brian_BH. Sorry to bother you. When you get a chance, if this card is good to go, would you mind pushing it. Only retagging you cause the original is technically incorrect so just want to get it out there to people.
I’m trying to develop the habit of not pushing things unilaterally, as a habit. In this case I think I’m the only one who has voted on it.
As a general rule, we’d like to have a world where for substantive changes there’s more than a single vote on a given suggestion. Ideally this is where I’d love to scroll down and see that, say, both Kevin and I have weighed in on it, and thus it goes through.
As a basic primer (I think this is broadly covered in some of the onboarding paperwork):
- 0 vote: real basic stuff; typo, etc.
- 1 vote: minor correction, little easy stuff.
- 2 votes: more substantive changes or alterations that need or benefit from some consensus. May not be major, but more significant than tiny correction/s.
- 3+ votes: big stuff.
I gave it the thumbs up so the changes have my blessing, but one thing I want to impress upon everyone is that pushing approvals will, necessarily, become a function of consensus as we build a team forward. This becomes more important the larger the team becomes, as it’s important for group dynamics (like consensus on suggestion voting) to take precedence over individuals.
Of course, being a maintainer means your suggestions (or mine, or Kevin’s), will naturally have more weight and receive more generous consideration as a natural consequence of the station but at the end of the day the healthiest approach is still for those same suggestions to pass through the same funnel (filter? What’s the better metaphor here?).
Since it already has my up-vote, it needs other eyes than mine. One thing I plan to put together in the next week or so is an all-call ping @ for all MCAT maintainers to make it easier to circle the wagon on a given suggestion, but I can’t put it together until a couple of other things are in place owing to the way the communication permissions are assigned
Using the process of tagging everyone and voting on bigger changes makes a ton of sense.
@kevinpanini any thoughts on this?
I was not too familiar with the topic so I tried to refrain but from my experience of what osmolarity is. My experience is that like you stated it is the concentration of molecules that are osmotically active.