OpenStudy (anonymous):

Please someone help explain this to me. Why does salt water boil at a lower temperature than tap water?

4 years ago
mathslover (mathslover):

Note : I am taking the salt as table salt ( $$NaCl$$ ) , just for an example. For making salt water, you have to first dissolve $$NaCl$$ (Sodium Chloride or Salt) in water ($$H_2 O$$ ) . The ions in sodium chloride ($$Na^{+}$$ and $$Cl^{-}$$ ) get dispersed in water. As hydrogen bonding is present in $$H_2 O$$ or water and it is hard to turn water into gas as it is a polar molecule. The ions in water, disrupts the hydrogen bonding and hence, this makes water boil at low temperature ( salt water ) . See, pure water has high boiling point than tap water and tap water has high boiling point than salt water. Do you know why? The pure water has no impurity to disrupt its hydrogen bonding while tap water has little salts also . But, salt water has the ions Na+ and Cl - which disrupts the hydrogen bonding. Hope you got it.

4 years ago
OpenStudy (anonymous):

Thank you so much. Thank you thank you thank you!

4 years ago
mathslover (mathslover):

4 years ago
OpenStudy (anonymous):

Really, thank you. I'm taking Chem and I had to do a project but the previous class work didn't give an explanation so I didn't understand the project very well. You're really great. Thank you, again!

4 years ago
mathslover (mathslover):

You're welcome again . And good luck for chemistry study.

4 years ago
mathslover (mathslover):

Interesting article : http://www.swri.org/10light/water.htm

4 years ago
OpenStudy (anonymous):

@mathslover shouldnt impurities elevate the boiling point?

4 years ago
OpenStudy (anonymous):

Isn't that factually incorrect. Salt water boils at a higher temperature than tap water, right?

4 years ago
mathslover (mathslover):

Yes, thinking the same... I just got stick to the questions' language.

4 years ago
OpenStudy (anonymous):

@aditkarekatte well, it should if it doesnt!

4 years ago
OpenStudy (anonymous):

@mathslover then how would u explain what @thisshouldfeellikefire asked?

4 years ago
OpenStudy (anonymous):

That was pretty much the essence of my question. Is it not a wrong question?

4 years ago
OpenStudy (anonymous):

It's a wrong question? I don't understand. I did the experiment and the salt water boiled at a lower temperature than the tap water did.

4 years ago
OpenStudy (anonymous):

Did you use pure water to dissolve the salt?

4 years ago
OpenStudy (anonymous):

Well if its tap water, that doesnt necessarily mean its pure! Depends on the hardness of the tap water! It might have dissolved salts too! Pure water as in distilled water would boil at a temperature lower than tap water!

4 years ago
OpenStudy (anonymous):

@thisshouldfeellikefire

4 years ago
OpenStudy (jfraser):

the wording of the question is incorrect. water with impurities will boil at a higher temp than pure (distilled) water because the added ions create additional IMFs that the solvent molecules must overcome in addition to the H-bonding IMFs that are normally present in water. If a sample of "salt water" was made with distilled water, and compared to a sample of tap water, if the tap water boils at a higher temp, then there must be more ions in the tap water than in the salt water.

4 years ago