Though, actually, apparently adding salt decreases the “specific heat capacity” of water, so that increasing it by N degrees requires less heat to be added (and therefore takes less stove time). The numbers in this article suggest that this makes a larger difference than the increased boiling point would.
(Though, again, the effect size seems to be epsilon for realistic amounts of salt people would add.)
The article has an egregious typo where they say “The pot containing a 20% salt concentration will heat up over 25 times faster”. I think they meant “over 25% faster”, which is either true or close-to-true. I’m not sure about the conclusion that cooking time goes (slightly) down; I think they’re holding total-mass fixed, but if we’re talking about “adding salt” then we should hold water-mass fixed instead, which adds onto the boiling point elevation effect and might tip the balance. I didn’t do the calculation because it’s entirely pointless. :-P
The graphs look like straight lines within the range from 0-5% salt concentration, so I’ll use the numbers at 5% and assume they scale down to the epsilon of salt one would actually add.
Density appears to increase by 4%.
Specific heat appears to go from 4200 to 3930 (edit: not 3850, whoops), a decrease of ~7%.
Boiling point … not present in your link, but this says approximately +0.5° C per 2.9% of salt, so let’s say at 5% salt it becomes 100.8°C. The delta from a starting point of, say, 21°C thus increases by about 1%.
Conclusion: time to boiling is multiplied by 1.04∗.93∗1.01=0.98, a (tiny) decrease.
Addendum: I see recommendations of 1 tablespoon of salt per gallon of water, which is 0.4% by mass, so in practice the time to boiling would be multiplied by more like 0.998.
I think you meant 3950 not 3850? And if we hold water-mass fixed instead of total-volume (i.e. the water is already in the pot and we’re deciding whether to add salt or not) we should use 5% not 4% (density doesn’t matter, because we don’t care whether the volume goes up a bit upon adding salt). Seems awfully close to even.
Though, actually, apparently adding salt decreases the “specific heat capacity” of water, so that increasing it by N degrees requires less heat to be added (and therefore takes less stove time). The numbers in this article suggest that this makes a larger difference than the increased boiling point would.
(Though, again, the effect size seems to be epsilon for realistic amounts of salt people would add.)
The article has an egregious typo where they say “The pot containing a 20% salt concentration will heat up over 25 times faster”. I think they meant “over 25% faster”, which is either true or close-to-true. I’m not sure about the conclusion that cooking time goes (slightly) down; I think they’re holding total-mass fixed, but if we’re talking about “adding salt” then we should hold water-mass fixed instead, which adds onto the boiling point elevation effect and might tip the balance. I didn’t do the calculation because it’s entirely pointless. :-P
Doing the math because I have the urge:
The graphs look like straight lines within the range from 0-5% salt concentration, so I’ll use the numbers at 5% and assume they scale down to the epsilon of salt one would actually add.
Density appears to increase by 4%.
Specific heat appears to go from 4200 to 3930 (edit: not 3850, whoops), a decrease of ~7%.
Boiling point … not present in your link, but this says approximately +0.5° C per 2.9% of salt, so let’s say at 5% salt it becomes 100.8°C. The delta from a starting point of, say, 21°C thus increases by about 1%.
Conclusion: time to boiling is multiplied by 1.04∗.93∗1.01=0.98, a (tiny) decrease.
Addendum: I see recommendations of 1 tablespoon of salt per gallon of water, which is 0.4% by mass, so in practice the time to boiling would be multiplied by more like 0.998.
I think you meant 3950 not 3850? And if we hold water-mass fixed instead of total-volume (i.e. the water is already in the pot and we’re deciding whether to add salt or not) we should use 5% not 4% (density doesn’t matter, because we don’t care whether the volume goes up a bit upon adding salt). Seems awfully close to even.