what is heavier? hot water or cold water?

Answer 1

Cold water, think of how convection works...the hot air rises, if you heat water the hot water rises. The cold air/water moves in to take its place...

Answer 2

Cold water is heavier since hot water evaporates the steam.

Answer 3

I don't believe they asked which is more dense, just which is heavier, assuming with equal moles in each case. In this case, the actual answer is that the hot water weighs a little (although negligibly) more! This is given to us by Einstein, who gave us the equation E=mc^2. Since the energy of the water is increasing, and the speed of light never changes, the mass must increase to accommodate. Most people are not aware of this neat little fact.

Answer 4

We understand that when you raise the temperature of a certain element, you also expand its volume. So since density is equal mass over the volume, then the hot water becomes less dense and therefore it weighs less notwithstanding that mass can not be created or destroyed. You should consider that within a certain boundary that the water occupies becomes less dense when heated and weighs less due to its volume expansion. The law of mass and energy conservation remains valid however, namely that matter and energy can neither be created nor destroyed. Look at this matter with regard to hot air! What happens to hot air when it is heated up? It flows upwards because it becomes less dense. So in this manner hot water would weigh less!

Answer 5

Hot water is lighter when compared to equal volume of cold water because water has expanded ====> increases volume =====> but weight/mass remains the same. So you will need less hot water to equal same volume of cold water.

Answer 6

Cold water.

Answer 7

the density of hot water is lower than that of cold water. For an equal volume hot water is lighter.

Answer 8

ON a per atom bases hot watter has aditional energy over the cold water atoms. Therefore the hot water atoms would contain more mass.The extra mass is very small only measurable in terms of the extra energy received from the heat source.
When the water cools it loses energy ;therefore its atoms would weight less.
Very imaginative and very vely interesting question.

Answer 9

Because water expands when it is heated, the same mass occupies a larger volume, i.e. mass equals density times volume M=D*V
A given volume of hot water weighs less than the same volume of cold water,

Answer 10

Mass is conserved either way. For the same number of molecules the hot water is heavier by E/c^2 of added energy to raise its temperature.