EK chemistry question not matching up with real life test results?

[Jack08]

---

Members don't see this ad.

First off, I only have a sample size of 2 tests. However, both went against what EK said. Can someone explain why?


EK Chemistry #662: If a small amount of salt were added to the substance forming a solution, which of the following represents the phase diagram of the solution??

Answer: When salt is added to any solvent, boiling point goes UP and melting point goes down.



So my mother always told me add salt to water to get it to boil faster. According to this book and my physics book she should be wrong. So we took 2 identical sized pans, same brand, model etc. We put each one on the stove side by side with 4 cups of water. Added some salt to one of the pans and watched them till they boiled. The salt water boiled first (but not by much, just about 15 seconds). Next we repeated the test again but switched the burners (to ensure 1 burner was not hotter than the other on level 10) and once again the salt water boiled first by about 17 seconds. How is this possible if the chem and physics books are saying it is the opposite, what am I missing?

Thanks mates!

 

[PlumbLine]

I believe all observations when cooking should be pretty negligible, but you are forgetting that raising the boiling point is not directly related to how long it takes to boil. When you're dealing with two different solutions, remember that they will have two different heat capacities.

I could be remembering this incorrectly, but despite salt water having a HIGHER boiling point than pure water, it heats up FASTER. I think it has to do with the molecules being able to bump into each other more readily (salt water has a lower heat capacity?).

 

[The Kraken]

http://www.knowswhy.com/why-does-salt-make-water-boil-faster/
The claim is that salt makes the water appear to boil faster. Next time try monitoring temperature, and kitchen observations aren't exactly isolated systems controlling variables 🙂