Is ice heavier or lighter than liquid water?

I would think it would weigh the same?
A scientific mind, I have not.
Good question though. Makes me think.

Ice is less dens than water, so it floats upon water.

Ice is in a special crystal lattice structure when it freezes, an arrangement that covers less volume than liquid water, thus ice is lighter than water. Less molecules of H2O in the same volume.

OK, the situation you have here is a fixed mass. You have the same amount of matter in the form of water as you do of ice, so they weigh the same.

You often hear that “ice is lighter than water” and this means that it’s less dense. This is why ice floats in water. Density is mass/volume. Since your mass is staying constant in this situation, the density changes by varying volume. The ice produced by a given mass of water takes up more space than the water did.

Easy way to remember this one: Which weighs more? A ton of feathers or a ton of steel?

@Adirondackwannabe beat me to it.

Which weighs more: pound of feathers or pound of gold? Answer: feathers, because a different system of ounces is used to measure gold.
Like others have said mass is not lost by freezing, but water ice has the unique property of being less dense in solid than liquid form, which is why ice floats.

This question is all about specific gravity (SG). The SG of water varies with the temperature. SG is the ratio of the density of a substance compared with the density of a reference substance.
Frozen pure H2O at 0ºC has a SG of 0.915 g/cc
Liquid pure H2O at 4ºC has a SG of 1.000 g/cc

The SG of frozen H2O is less than liquid H2O therefore frozen H2O floats on liquid H2O.

Ice floats.

Water is so weird they STILL don’t really know how it works. Ice, thank goodness, starts forming on the surface and not at the bottom. That is why we are here.

The weight does not change, the volume changes.

In general, freezing won’t change the weight of the water. In general.

In actuality, however, the freezing process by which liquid water gives up its heat until it reaches a freezing temperature (which is, after all, what is happening) generally occurs as some water vapor evaporates as the heat radiates from the water. So some volume of water is lost, depending on wind and weather conditions (while outside) or the operation of the refrigeration equipment (in a freezer). In addition, as the water stays frozen and the environment does not stay static – no matter how it appears to you, because you can’t sense all of the subtle environmental changes – some additional volume of water is lost via continuing evaporation and transpiration. That is, the ice gradually undergoes a phase change from solid to gas (water vapor) without appearing to melt. (You can see this happen very gradually to ice and snow during winter in northern latitudes during long dry spells after a snow or ice storm. The ice and snow don’t “melt”, but they do gradually disappear through the weather.)

But for all intents and purposes unless you’re being highly precise, “freezing doesn’t change the weight” of water.

What does happen, however, is that the ice expands the volume of the water. You already know this, right? So what has happened is the density of ice is less than the density of liquid water, which is why ice floats.

It would weigh the same in ice and liquid form. Although ice is less dense since it exands when freezing, it is still the same weight as was the amount of liquid water that was used to create it. Ice still floats in water due to the fact it is less dense.

Here is another curious fact. Suppose you have an ice cube floating in a glass of water. If we ignore the amount of water lost to evaporation, what happens to the level of the water in the glass as the ice cube melts? It remains the same. The weight of water displaced by the ice cube equals the weight of the ice cube, so the level of the water is based on the weight of the water plus the weight of the ice cube, which remains constant, ignoring evaporation.

Weight will be same in liquid & solid form but it may change if we are talk about the vapour form.

^ I agree with your first paragraph but not the second. When you stipulate that you have a kilo of each substance, you are defining them to be equal in mass/weight, so it’s kinda nonsensical to then say that the ice weighs more. The difference is that the ice will take up more volume.

But anyways, welcome to Fluther :)