In this brief guide, we are going to answer the question “does salt cause water to boil faster” with an in-depth analysis of whether or not the addition of salt in water causes it to boil faster. Moreover, we are going to discuss the boiling point elevation along with some examples.
So without much ado, let’s dive in and figure out more about it.
Does salt cause water to boil faster?
There are a couple of phenomena that decide whether or not saltwater boils faster than freshwater.
- Specific heat capacity
- Boiling point elevation
Specific heat capacity
Firstly there comes the specific heat capacity which is the energy or the amount of heat that is needed to produce a unit change in the temperature of a given mass of a substance.
The specific heat of freshwater is 4.184 kJ/K kg while that of seawater is 4.009 kJ/K kg (owing to the fact that it has 3.5% dissolved salts in it). So it will take 4.009 kJ of heat to raise the temperature of 1 kg seawater while it takes 4.184 kJ of heat to raise the temperature of 1 kg fresh water by 1 Kelvin. Therefore seawater boils faster than fresh water and we can safely say that saltwater also boils faster than freshwater. But that’s not all, another phenomenon is taking place behind the scene and that is boiling point elevation.
Boiling point elevation
So when it comes to saltwater, it has a higher boiling point than fresh water. The reason behind this phenomenon is that saltwater contains an extra amount of solute as compared to freshwater, so what happens is that whenever some solution has more number of particles (non-volatile compounds) present in it as compared to its pure form, its boiling point increases.
So it is a rule that the higher the quantity of non-volatile compounds present in the formulation of a liquid, the higher it will take to boil because of the increased number of particles, thus the higher will be the boiling point of that liquid. As saltwater contains more non-volatile compounds therefore it has a higher boiling point than fresh water and this phenomenon is known as boiling point elevation.
Now here is the catch to both of the processes, we have to add a lot of salt in the water to see the significant impact of both these phenomena (as we have seen that it needed to be 3.5% salt solution to decrease the specific heat from 4.184 kJ/kg to 4.009 kJ/kg and you can estimate the saltiness of this solution by considering the taste of the seawater. All of us do not want our food to be that much salty therefore the addition of a pinch or two of salt won’t have any noticeable effect.)
So what we inferred from all this discussion is that the addition of salt lowers the specific heat but increases the boiling point so we can say that both the processes nullify the impact of each other. Thus the addition of salt does not have any significant effect on the time that it takes for water to boil.
So if you are adding the salt just to make the water boil faster, we recommend you to leave it as it is, as the addition of salt won’t make the water boil faster.
What is the boiling point elevation?
Boiling point elevation is the phenomena in which the boiling point of a solution becomes higher than the boiling point of the pure liquid (solvent). The boiling point elevation is a colligative property of the matter which means that it depends on the number of particles that are added to the solution.
It is worth mentioning here that the boiling point elevation like other colligative properties does not depend on the mass of the particles or the type of particles that are added to the solvent.
The most common examples of the boiling point elevation can be seen by the addition of salt in water. Moreover, the same phenomenon is the reason lying behind the higher boiling point of milk as compared to the water (no doubt milk consists of a large quantity of water but milk is essentially an emulsion that contains other molecules like fats and proteins. Therefore these molecules raise the boiling point of milk).
You can read more about the colligative properties of solutions here.
In this brief guide, we answered the question “does salt cause water to boil faster” with an in-depth analysis of whether or not the addition of salt in water causes it to boil faster. Moreover, we discussed the boiling point elevation along with some examples.