How much water can i put in 500ml plastic container and microwave till hot?

[orabrush]

I want to keep something warm for a few hours and I am going to use a container of plastic hot water.

[nevillesdaughter]

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@j*oono wrote:

Hehehe.  Might pay to add a little extra and I had it the wrong way around.  Water expands when it freezes, not when it boils.... I think 

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Water is one of the very few (only?) compounds that expand both when it is heated and frozen.

Marina.

[garry9922]

500ml of water will not retain its heat for several hours. If you want to keep something warm for this length of time, you should sit on it, For more information on this, google "incubation".

[sineaterdoodah]

lol,garry! 

OP,is something you need to keep warm during transport? is that why you want to use a hot water bottle sort of thing? because garry is correct,that wouldn't maintain temp for long. at least,not without being enclosed in an insulated bag.