Sorry the format sucks, I’m on mobile.
So, I have a 4 month old. On occasion I warm formula that has been in the fridge in the microwave. 20 seconds, All it needs. Yes, I shake it and test it on my arm everytime to make sure it is just right and i barely do this as i have a baby brezza. Don’t come at me. Lol.
Now today my 9 year old who is dealing with sensitive teeth asked me is I could warm her pear juice for her. Sure, no prob. The pear juice took 40 seconds just to reach room temperature. Why is this? Is it the sugars? I don’t know why this just occured to me and is bothering me but here we are.
In: Chemistry
If you look at [This Gif](https://lh3.googleusercontent.com/proxy/dX6cV5Tlq8gQS98Xk6CLmkUgVEXG62OY3zSbtGfW8omcECLehyV8L-NllN16thf_ljpCBRHDbMP7I69NUILBTaEAFlfjzFL3BjzR8nTX4qg_ZA) you can see how a single molecule of water can distribute extra kinetic energy through different modes of vibration.
If one unit of energy causes one of those modes of vibrations, then it requires one unit of energy for *each* type of vibration for a one unit increase in the temperature.
Water is unique in that it has a very high number of modes of vibration compared to many other substances. Because each mode of vibration requires its own unit of energy, then the more modes of vibration available, the more energy will be required to increase the temperature.
This is known as the *specific heat* and is a quantitative measure of the relationship between energy and temperature.
The second thing to keep in mind is how a microwave works. Microwaves are explicitly designed to cause high energy vibrations in water, and lesser energy vibrations to anything that is not water.
As formula will contain more water content than a pear for equal mass, it should take longer for the pear to heat up, because the pear has many components that are not sensitive to microwaves.
However if you were to heat them up in an oven for example, the pear has a much better chance of heating up quicker, as now the sensitivity to microwaves is no longer a limiting factor. The pear takes less total energy to heat up, but the formula gets an extra kick from the microwave specifically.
This is to do with what’s called heat capacity.
Heat capacity is an extensive property that determine how much energy is required to increase its temperature.
Heat capacity is determined by 3 factors: the change in temperature, the mass of what’s being heated and finally substance and phase of the substance.
The main reason why something will heat quicker in an example of water or alcohol is density difference between the two liquids but there are many factors such as initial viscosity, other compounds in the liquid etc that can reduce or increase a liquid heat capacity
Unfortunately there isn’t an easy way to expand on this from my knowledge as it involves lots of complex maths and I’m not good at explaining maths haha
it’s to do with the bonds in between the atoms that are in the juice. the stronger the bonds, the higher the temperature. take this with. spinach of soat tho. other replies will be better
There are two factors at play here. Absorptivity and specific heat. Specific heat is how much raw energy it takes to heat something up. More specific heat makes things heat up slower because it requires more energy for them to do so.
Absorptivity matters when you heat something with light, including microwaves and to a lesser extent traditional ovens. This is what percentage of the incoming energy is absorbed versus just reflected. This is why black surfaces heat quickly in the sun, while white surfaces do not.
It is also worth noting that larger volumes of stuff will heat more slowly, of course.
More stuff thats dissolved in water, the higher the temperature that it will boil. Imagine the particles in water getting in the way of the water molecules to make it harder for them to escape as gas
It doesnt matter whats dissolved in it, what matters is how much is dissolved.
This is called boiling point elevation
Edit: This is assuming we are talking about two liquids made up of water. If you have two different liquids then there is more to it, as explained by other comments.
Something called specific heat capacity means that liquids like water require more energy to make them boil https://youtu.be/18pK7rPtAAk
However there is also the issue with microwaves which use dielectric heating, basically rotating a molecule back and forth which water does very easily, but fat doesn’t https://youtu.be/V0dtq3rCEjw
ELI5: Some things take more energy to heat up than other things. The microwave outputs a specific amount of heat per second, therefore things that require more heat need to be in the microwave longer.
ELI’mOlder: Everything has a property called “specific heat” or “heat capacity” (different names, same concept.) For example, water takes 4.184 Joules (a measure of energy) to heat up 1 gram by 1 degree Celsius.
Ethanol (drinking alcohol) takes 2.18 Joules to heat up 1 gram by 1 degree Celsius.
Different things take different amounts of energy to heat up by the same amount of temperature. Water takes more energy (more time in the microwave) to heat up by 10 degrees than ethanol would to heat up the same 10 degrees. Furthermore dissolving THINGS inside of the water can also increase (or decrease) this amount of energy. (Sugar, salt, etc.) There are mathematical equations we can use to calculate how MUCH these things affect the heat capacity, but I won’t go into them.
Thank you everyone!! As I was reading this it became more clear, and I’m pretty sure I learned all of this at some point. But I have been very sleep deprived.
I enjoyed reading every comment. Very helpful and informative. Thank you so much ❤
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