Ionic bonds in solutions

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Ionic bonds in solutions

Postby 605324529 » Sun Feb 02, 2020 7:12 pm

Are ionic bonds broken when salt dissolves in water? And if so, then is dissolving a chemical change?

Aliya Jain 2B
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Re: Ionic bonds in solutions

Postby Aliya Jain 2B » Sun Feb 02, 2020 7:27 pm

I think ionic bonds are breaking, but I think the dissolving of salts is a physical change

Anuradha S 1F
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Re: Ionic bonds in solutions

Postby Anuradha S 1F » Fri Mar 13, 2020 8:23 pm

Ionic bonds between the ions are broken but they are replaced by hydrogen bonds with the oppositely charged atom in a water molecule. I.e. when NaCl is dissolved in water, Na+ forms a hydrogen bond with negatively charged oxygen.

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Re: Ionic bonds in solutions

Postby Nan_Guan_3J » Thu Oct 08, 2020 10:00 am

ionic bonds are broken. but dissolution is a physical process because ionic bond is a type of intermolecular bond. no intramolecular bond is broken here and there are no new compounds generated.

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Re: Ionic bonds in solutions

Postby TrishaP_3E » Thu Oct 08, 2020 12:38 pm

Intermolecular forces (the breaking of which is a physical change) are interactions between multiple molecules. For example, if two NaCl molecules are bonded together, there are bonded by intermolecular forces. Intramolecular forces (the breaking of which is a chemical change) are the forces between multiple atoms that allow the formation of one molecule. For example, the ionic bond between Na+ and Cl- in NaCl is an intramolecular force.

When salt dissolves in water, NaCl is broken into Na+ and Cl- ions that then bond to different parts of the water molecules. As the very molecule of NaCl is broken apart, in this case intramolecular forces are broken, and the process is a chemical change.

Sami Siddiqui 3L
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Re: Ionic bonds in solutions

Postby Sami Siddiqui 3L » Thu Oct 08, 2020 12:59 pm

I have to agree with Trisha on this one. Ionic bonds are, in fact, intramolecular bonds because they exist within the compounds themselves, not in between like intermolecular forces (e.g., dispersion forces, hydrogen bonding, etc.). With that being said, dissolving ionic compounds would technically be a chemical process because the intramolecular bonds are effectively broken (as water molecules create hydration shells around ions) and energy changes occur.

Katie Phan 2H
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Re: Ionic bonds in solutions

Postby Katie Phan 2H » Thu Oct 08, 2020 4:30 pm

I think there's a lot of confusion with whether dissolving salt in water is a chemical or physical change since when you boil off water you end up with salt, but I'm going to have to agree with Sami and Trisha since ionic bonds are intramolecular.

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Re: Ionic bonds in solutions

Postby reva_bajjuri » Thu Oct 08, 2020 9:07 pm

this might be kind of a silly question, but when solutions are aqueous, how come molecules don't lose their structure/come apart? can ionic substances exist in aquous solutions?

Helena Hu 3E
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Re: Ionic bonds in solutions

Postby Helena Hu 3E » Fri Oct 09, 2020 9:59 pm

I don't know if I am understanding your question-- are you asking why molecules do not break apart when they are dissolved in aqueous solutions? ex. table salt (NaCl) being dissolved in water?
The answer to this example is that water molecules interact with Na to pull the NaCl ions apart.
I don't know if I answered your question, but I hope this might help!

Scot Widjaja Dis 1J
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Re: Ionic bonds in solutions

Postby Scot Widjaja Dis 1J » Sun Oct 11, 2020 9:36 am

Yes, the ions Na+ and Cl- in salt dissociate and dissolve when mixed with water because the partial negatively charged oxygen atoms in water attract the positively charged sodium ions and the partial positively charged hydrogen atoms attract the negatively charged chloride ions. However, dissolving is not a chemical change. By definition, a chemical needs to be an irreversible process and while dissolving salt in water does involve the breaking of ionic bonds, when water evaporates, the salt particles begin to reappear and therefore, it is a physical change.

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