hydrogen bonding

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alanaarchbold
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hydrogen bonding

Postby alanaarchbold » Tue Nov 13, 2018 2:51 pm

How does hydrogen bonding explain higher melting points?

ChathuriGunasekera1D
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Re: hydrogen bonding

Postby ChathuriGunasekera1D » Tue Nov 13, 2018 2:54 pm

Hi! Hydrogen bonding is stronger than most intermolecular forces, so it is requires more energy to break those IMFs, and therefore needs a higher temperature for the compound to move from solid to liquid.

Alexa_Henrie_1I
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Re: hydrogen bonding

Postby Alexa_Henrie_1I » Tue Nov 13, 2018 8:36 pm

^Exactly. Higher melting points indicate more stability so this explains the example given in class: GC base pairs in DNA are more stable than AT base pairs.

Nicolette_Canlian_2L
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Re: hydrogen bonding

Postby Nicolette_Canlian_2L » Tue Nov 13, 2018 8:44 pm

Alexa_Henrie_3B wrote:^Exactly. Higher melting points indicate more stability so this explains the example given in class: GC base pairs in DNA are more stable than AT base pairs.

So does this mean GC base pairs have stronger bonds than AT base pairs?

Kassidy Tran 1E
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Re: hydrogen bonding

Postby Kassidy Tran 1E » Tue Nov 13, 2018 10:35 pm

Nicolette_Canlian_3G wrote:
Alexa_Henrie_3B wrote:^Exactly. Higher melting points indicate more stability so this explains the example given in class: GC base pairs in DNA are more stable than AT base pairs.

So does this mean GC base pairs have stronger bonds than AT base pairs?

Yes, because G-C base pairs have three hydrogen bonds rather than two, like in A-T base pairs. Since there are more hydrogen bonds, it has a higher melting point.

Hannah Pham 1D
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Re: hydrogen bonding

Postby Hannah Pham 1D » Thu Nov 15, 2018 2:20 pm

Hydrogen bonding takes more energy to break because it is stronger than most intermolecular forces.

Aurbal Popal
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Re: hydrogen bonding

Postby Aurbal Popal » Thu Nov 15, 2018 2:50 pm

Chathuri Gunasekera 1G wrote:Hi! Hydrogen bonding is stronger than most intermolecular forces, so it is requires more energy to break those IMFs, and therefore needs a higher temperature for the compound to move from solid to liquid.


I thought covalent bonds and ionic bonds were stronger? Or do those not count as IMF?

Nicolette_Canlian_2L
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Re: hydrogen bonding

Postby Nicolette_Canlian_2L » Thu Nov 15, 2018 6:20 pm

Kassidy Tran 1F wrote:
Nicolette_Canlian_3G wrote:
Alexa_Henrie_3B wrote:^Exactly. Higher melting points indicate more stability so this explains the example given in class: GC base pairs in DNA are more stable than AT base pairs.

So does this mean GC base pairs have stronger bonds than AT base pairs?

Yes, because G-C base pairs have three hydrogen bonds rather than two, like in A-T base pairs. Since there are more hydrogen bonds, it has a higher melting point.

ahhh I see. Thank you!

Ahmed Mahmood 4D
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Re: hydrogen bonding

Postby Ahmed Mahmood 4D » Sun Nov 18, 2018 11:12 pm

Hydrogen bonding is extremely strong. Because of this, it takes more heat to break hydrogen bonds, leading to higher melting points among hydrogen bonds.

Pritish Patil 1K
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Re: hydrogen bonding

Postby Pritish Patil 1K » Sun Nov 18, 2018 11:51 pm

Hydrogen bonding is stronger than most other IMF so it takes more energy to break.

505211599
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Re: hydrogen bonding

Postby 505211599 » Mon Nov 19, 2018 12:23 am

Hydrogen bonding is the strongest IMF so the energy needed to separate these molecules is higher. Therefore the melting point would be higher.

ChathuriGunasekera1D
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Re: hydrogen bonding

Postby ChathuriGunasekera1D » Tue Nov 20, 2018 8:06 am

Aurbal Popal wrote:
Chathuri Gunasekera 1G wrote:Hi! Hydrogen bonding is stronger than most intermolecular forces, so it is requires more energy to break those IMFs, and therefore needs a higher temperature for the compound to move from solid to liquid.


I thought covalent bonds and ionic bonds were stronger? Or do those not count as IMF?


Covalent bonds and ionic bonds are between the atoms within the molecules (called INTRAmolecular forces). The bond between the C and H is covalent in methane (intramolecular force), but the bond between H and H that connect whole methane molecules to each other is a dispersion force (intermolecular force).

It gets a little bit confusing because ionic bonding can occur between Na and Cl within an individual salt molecule, but it also occurs between the Na of one molecule and the Cl of another molecule. So technically, ionic bonding is both an intramolecular force and an intermolecular force. The same cannot be said about covalent bonds.

Going back to boiling point; when you heat a substance, you are breaking apart one molecule from another, not the individual atoms in one molecule. For example in methane, you are separating one CH4 from another, not one CH4 into one C and 4 Hs. Covalent and ionic bonding (the intra type) is not considered when determining boiling point. Hope I answered the question!


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