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Sapling #13

Posted: Sun Nov 15, 2020 6:39 pm
by IreneSeo3F
Hi! I'm having difficulty with problem 13 in sapling assignment.
The problem asks:
what is the maximum theoretical number of water molecules that one urea molecule can hydrogen bond with?
How can I solve this?

Re: Sapling #13

Posted: Sun Nov 15, 2020 6:55 pm
by Bronson Mathos 1H
I solved this using the N, O, and F rule of hydrogen bonding by locating and counting all the possible points on the structure where a hydrogen bond could occur and that total should give you your answer as the question implies that the water molecules would bond to urea using hydrogen bonds.

Re: Sapling #13

Posted: Sun Nov 15, 2020 6:59 pm
by Leo Naylor 2F
Also, each lone pair on an atom like nitrogen can form a hydrogen bond, as long as you ignore that the space might not be enough for two water molecules. Thus, the answer might be more than you originally thought. Hope this helps!

Re: Sapling #13

Posted: Sun Nov 15, 2020 7:01 pm
by Kimiya Aframian IB
IreneSeo3F wrote:Hi! I'm having difficulty with problem 13 in sapling assignment.
The problem asks:
what is the maximum theoretical number of water molecules that one urea molecule can hydrogen bond with?
How can I solve this?

Hi! For this problem you need to consider the circumstances that allow for hydrogen bonding. Those circumstances are an H atom bonded to another highly electronegative atom. Another location would be where there is an N, O, or F that has a lone pair of an electrons. Hope this helps!

Re: Sapling #13

Posted: Sun Nov 15, 2020 7:07 pm
by Jessica Hu 3L
Adding onto this, I ended up figuring this out, but I'm still confused about the exact number, I counted the atoms most likely to form a Hydrogen bond but that number was less than the number I ended up getting.

Re: Sapling #13

Posted: Sun Nov 15, 2020 7:07 pm
by Rachel Kho Disc 2G
Make sure you count the hydrogen bonds that are already in the urea molecule, because that's where I made a mistake. Initially, I only counted the hydrogen bonds that COULD form and so it took me a few tries to get to the right answer.

Re: Sapling #13

Posted: Sun Nov 15, 2020 8:23 pm
by David Liu 1E
you locate the amount of N,O,and F atoms that a hydrogen bond can form, and then you check how many lone pairs each one of these have for a hydrogen bond to form with!

Re: Sapling #13

Posted: Mon Nov 16, 2020 12:02 am
by Lillian
Jessica Hu 3L wrote:Adding onto this, I ended up figuring this out, but I'm still confused about the exact number, I counted the atoms most likely to form a Hydrogen bond but that number was less than the number I ended up getting.

The exact amount is 8 I'm pretty sure. For each hydrogen atoms, the oxygen in a water molecule will bond (which makes 4). For each lone pair of electrons on one of the electronegative atoms, the hydrogen in a water molecule will bond (another 4). This adds up to 8. Hope this helps! :)

Re: Sapling #13

Posted: Tue Nov 17, 2020 2:46 pm
by Jessica Hu 3L
Lillian wrote:
Jessica Hu 3L wrote:Adding onto this, I ended up figuring this out, but I'm still confused about the exact number, I counted the atoms most likely to form a Hydrogen bond but that number was less than the number I ended up getting.

The exact amount is 8 I'm pretty sure. For each hydrogen atoms, the oxygen in a water molecule will bond (which makes 4). For each lone pair of electrons on one of the electronegative atoms, the hydrogen in a water molecule will bond (another 4). This adds up to 8. Hope this helps! :)


Oh that makes a lot of sense thanks!

Re: Sapling #13

Posted: Sun Nov 29, 2020 5:09 pm
by Lillian
Jessica Hu 3L wrote:
Lillian wrote:
Jessica Hu 3L wrote:Adding onto this, I ended up figuring this out, but I'm still confused about the exact number, I counted the atoms most likely to form a Hydrogen bond but that number was less than the number I ended up getting.

The exact amount is 8 I'm pretty sure. For each hydrogen atoms, the oxygen in a water molecule will bond (which makes 4). For each lone pair of electrons on one of the electronegative atoms, the hydrogen in a water molecule will bond (another 4). This adds up to 8. Hope this helps! :)


Oh that makes a lot of sense thanks!


Yey! Glad it helped :))