Week 10 Sapling #6

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Madisen Brown -1C
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Joined: Wed Sep 30, 2020 9:49 pm

Week 10 Sapling #6

Postby Madisen Brown -1C » Fri Dec 11, 2020 3:45 pm

I seem to be having difficulty identifying the "weak bases" and "other" categories for this problem. I thought that NH3 and NaCl would be weak bases but I've attempted this solution so many times and I seem to not be understanding something. If someone could help me out that'd be great.
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Courtney Situ 2B
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Re: Week 10 Sapling #6

Postby Courtney Situ 2B » Fri Dec 11, 2020 3:48 pm

Hi there!

NH3 is a weak base since it can donate electrons or accept protons from the nitrogen lone pairs. However, NaCl is not an acid or a base; it's a salt. I think you'd have to put it in the other category.

Hope that helps! :))

Madisen Brown -1C
Posts: 54
Joined: Wed Sep 30, 2020 9:49 pm

Re: Week 10 Sapling #6

Postby Madisen Brown -1C » Fri Dec 11, 2020 4:09 pm

Courtney Situ 3D wrote:Hi there!

NH3 is a weak base since it can donate electrons or accept protons from the nitrogen lone pairs. However, NaCl is not an acid or a base; it's a salt. I think you'd have to put it in the other category.

Hope that helps! :))

Yes, this helped! Thank you so much

Earl Garrovillo 2L
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Re: Week 10 Sapling #6

Postby Earl Garrovillo 2L » Fri Dec 11, 2020 4:10 pm

The way the book defines weak acid/base is any acid/base classified as strong. https://sites.google.com/site/chempendi ... cids-bases . So any acid/base not listed here is considered weak.

Since none of the ones you still have left are on the strong acid/base list they are all weak/other
NaCl: is a salt since it lacks H+ or OH- and both ions are from a strong acid/base so that automatically places it in the "other" category.
NH3: weak base since it has a lone pair of electrons and can accept a proton
CH3NH2: weak base since it's a derivative of NH3 (one of the H is replaced with the CH3) so the same reason as above
H3PO4: weak acid. The phosphate ion has a -3 charge, since there's 3 H+ ions bonded, it's more likely for H3PO4 to lose an H+ than to gain one. You can also remember H3PO4 as the conjugate acid of H2PO4-

Jiapeng Han 1C
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Re: Week 10 Sapling #6

Postby Jiapeng Han 1C » Sat Dec 12, 2020 4:17 am

NH3 is indeed a weak base as it could donate lone pair of electron. However, NaCl is a salt because when it dissolves in water, both ions will form ion-dipole attraction with water molecules. It is a mere physical process as nothing is really changed.

Savannah Torella 1L
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Re: Week 10 Sapling #6

Postby Savannah Torella 1L » Sat Dec 12, 2020 6:52 pm

I was also having trouble with this problem at first. Acids start with an H or end with COOH. Strong bases often start with a metal and end in OH, and weak bases often contain N. Since NaCl does not contain H+ or OH-, it would be neither an acid or a base. It's actually a salt.

Nathan Tong 3G
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Re: Week 10 Sapling #6

Postby Nathan Tong 3G » Sat Dec 12, 2020 6:58 pm

The easiest way to solve this problem would be to first organize the molecules into acids and bases, depending on whether it would want to accept or donate a proton. Then, you could remember which molecules are considered strong acids/bases as noted in the chart Earl provided, and split the acids and bases according to that. Finally, since NaCl is neither an acid nor base, it would go in the other category.

Melanie Lin 3E
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Joined: Wed Sep 30, 2020 9:38 pm

Re: Week 10 Sapling #6

Postby Melanie Lin 3E » Sat Dec 12, 2020 8:52 pm

Hi! NH3 is a weak base but NaCl isn't. I think the best way to sort of reason that is because when it is put into aqueous solution, NaCl dissociates into Na+ and Cl-. Both of these ions stay that way and don't contribute or take any H+ protons in the solution so pH does not change. Hope this helps!


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