# Viscosity of Honey decreases. But why?

• NuGG
In summary: For AS Level physics I had to do some coursework on the viscosity of Honey. I found out that as the temperature of the honey increases, its viscosity decreases.I drew the conclusion that, when a substance is heated, its molecules move farther apart and faster, so therefore, if the molecules are moving farther apart, the substance will expand. This reduces the density of the Honey and lowers the viscosity, allowing the ball-baring to fall through the Honey faster.However, I have been told this is not the actual reason for why the viscosity of the honey decreases, and that it has something to do
NuGG
For AS Level physics I had to do some coursework on the viscosity of Honey. I found out that as the temperature of the honey increases, its viscosity decreases.

I drew the conclusion that, when a substance is heated, its molecules move farther apart and faster, so therefore, if the molecules are moving farther apart, the substance will expand. This reduces the density of the Honey and lowers the viscosity, allowing the ball-baring to fall through the Honey faster.

However, I have been told this is not the actual reason for why the viscosity of the honey decreases, and that it has something to do with Helium atoms (in other words, ask a chemist).

Can anyone tell me why the viscosity decreases?

I’ve been stuck on this for a while and ill be grateful for any help.

Cheers,

NuGG

Please explicate how reduction in density implies reduction in viscosity. Better yet, show a derived equation where viscosity is proportianal to density.

I don't think we need to deal with He atoms to explain this effect.

Viscosity (talking about liquids) is a function of the cohesive bonding forces present in the substance. Since in a liquid, the cohesive bonds are pretty high, the fluid has a hard time allowing adjacent layers "slip" past one another (think of pushing a stack of playing cards from the top). It all goes to intermolecular forces.

Now, I am no honey expert or chemist, but I was surprised to see helium as your clue. I was under the impression that honey is a complex sugar which is carbon, hydrogen and oxygen of course there is water in there as well. I have no idea where the helium is coming from. Perhaps someone else can elaborate on that.

That also reminds me, I would note in your analysis two other items:
1) The viscosity of honey has to be dependant on how much water is in it.
2) I don't have any sources to prove or disprove, but I would be cautious in considering honey to be a Newtonian fluid (I don't know if you really need to go that far into this, but I thought I'd mention it).

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I'd imagine that NuGG's clue was 'hydrogen', rather than 'helium' as he has stated.

NuGG, do a bit of reading on hydrogen bonding and see if you get anywhere.

NuGG said:
For AS Level physics I had to do some coursework on the viscosity of Honey. I found out that as the temperature of the honey increases, its viscosity decreases.

I drew the conclusion that, when a substance is heated, its molecules move farther apart and faster, so therefore, if the molecules are moving farther apart, the substance will expand. This reduces the density of the Honey and lowers the viscosity, allowing the ball-baring to fall through the Honey faster.

However, I have been told this is not the actual reason for why the viscosity of the honey decreases, and that it has something to do with Helium atoms (in other words, ask a chemist).

Can anyone tell me why the viscosity decreases?

I’ve been stuck on this for a while and ill be grateful for any help.

Cheers,

NuGG

I'd say that you're in the ballpark, and am very puzzled by whoever is asking you to look at "helium atoms". Fred has given you a pretty good answer that I would agree with (that's why it's good! . In addition, here's a link for you to read all about viscosity more than you would ever care for:

http://hypertextbook.com/physics/matter/viscosity/

Zz.

brewnog said:
I'd imagine that NuGG's clue was 'hydrogen', rather than 'helium' as he has stated.

Sorry i think it was hydrogen actualy. My mistake.

Ive done some more reserch and added some information on cohesive bonds etc to my conclusion, however i still cannot find anything useful for Hydrogen atoms. I presume it has something to do with the Hydrogen bonds...

Any one got any ideas?

Cheers,

NuGG

## 1. Why does the viscosity of honey decrease over time?

The viscosity of honey decreases over time due to a process called thixotropy. This is a phenomenon where the structure of a material, in this case, honey, breaks down over time when exposed to stress or agitation. As the honey is stirred or poured, the bonds between its molecules break, resulting in a decrease in viscosity.

## 2. Does the temperature affect the viscosity of honey?

Yes, temperature has a significant effect on the viscosity of honey. As the temperature increases, the viscosity of honey decreases. This is because the heat energy causes the molecules in the honey to move faster, resulting in a weaker bond between them and a decrease in viscosity.

## 3. How does the water content of honey affect its viscosity?

The water content of honey plays a crucial role in its viscosity. Honey with a higher water content will have a lower viscosity as the water molecules act as lubricants, making it easier for the honey molecules to slide past each other. On the other hand, honey with a lower water content will have a higher viscosity as there are fewer liquid molecules to act as lubricants.

## 4. Is the type of honey a factor in its viscosity?

Yes, the type of honey does impact its viscosity. Different types of honey have varying amounts of sugars, which can affect the strength of the bonds between the molecules. For example, honey with a higher fructose content will have a lower viscosity compared to honey with a higher glucose content.

## 5. Can the viscosity of honey be reversed?

No, once the viscosity of honey has decreased, it cannot be reversed. This is because thixotropy is a permanent change in the structure of the honey caused by the breakdown of bonds between molecules. However, the viscosity can be temporarily increased by cooling the honey or adding substances like cornstarch or guar gum, which can thicken the honey.

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