is water heavier in weight when cold or hot?

Answer 1

In weight, it's the same. No mass has been added or taken away by heating it or cooling it down, weight doesn't care about tempurature except possibly at phase changes.

It does however become more dense until about 4 degrees centigrade, so water of a certain volume at 4 degrees centigrade ways more then water of the same volume at 10 degrees centrigrade. This is because the 4 degree centigrade water is more dense so to get the same volume you need to add more mass.

Answer 2

Assuming that
1. The water stays in liquid phase (i.e. does not get so cold that it freezes into ice or gets so hot that it boils into steam), and
2. The mass of the water is constant,

The weight will not change.

This is because the weight of water is equal to the product of the mass of water and the gravitational field strength of the Earth(roughly 9.81 N/m). The gravitational field strength of the Earth is assumed constant when the water used is on (or near) the surface of the Earth (it would be considered to be smaller if measured at a large distance from the Earth's surface). The weight of the water is therefore directly proportional to the mass of water. Since when we heat or cool water we do not lose any of its mass (assuming point 1.) the weight will not change.

Answer 3

The weight(mass) of water will not change, but the density and volume will. Water is most dense and least volume at 4 deg. Celcius or 277.16K (Kelvin). Both below and above this temperature the density decreases, hence the volume increases to keep the mass constant. Therefore ice floats allowing life to survive under a frozen surface.

Formula: Density(D) = mass(M) / Volume(V)

Answer 4

It depends how cold (warm) the water is.

From Wikipedia:

"liquid water becomes denser with lowering temperature, just like other substances. But at 4 °C, just above freezing, water reaches its maximum density, and as water cools further toward its freezing point, the liquid water, under standard conditions, expands to become less dense."

"Heavier" until it gets to just above freezing, but then it gets "lighter". That's why ice forms on top of a lake, and ice cubes float in water.

Answer 5

Stated more correctly, you are asking how the density of water changes with temperature. Water reaches its maximum density just above the freezing point, namely at 4 degress Celsius. As it gets colder, it expands as ice crystals start to form. This explains why ice floats instead of sinks.

As water warms above 4 degrees its density constantly decreases until it turns to steam at 100 degrees - at sea level. Without an atmosphere to exert pressure, liquid water cannot exist: frozen water on the moon, for example, 'sublimes' directly into vapor with no liquid phase, the same way dry ice (frozen carbon dioxide) does here on earth.

Answer 6

a pound of water is always a pound of water.

I believe you are asking about density of water. Water is one substance that actually expands as it approaches freezing- most materials contract as they cool and freeze. This makes the same volume of water a little lighter and go to the top of the pond before freezing. This phenomenon is responsible for allowing water life to continue under the ice. Getting back to your question 1 cubic foot of cold water is lighter than 1 cubic foot of a little bit warmer water. This holds for temperatures between 32 and about 36 degrees F. Once you get passed that, water follows the same as other materials.

Answer 7

water's density (mass per unit volume) increases as the tmeperature decreases, until it reaches approx 4 degrees Celcius at which point the density decreses. this is why ice floats in water.

Answer 8

If the original volume is the same to start, it would weigh the same if it has not started to evaporate. So when you mean hot, the state at which it starts to evaporate that is steam.

Answer 9

1kg of cold water is the same as 1kg of steam its their volume thats affected by heat not their mass

Answer 10

Weight: 62.416 pounds per cubic foot at 32°F
Weight: 61.998 pounds per cubic foot at 100°F
Weight: 8.33 pounds/gallon, 0.036 pounds/cubic inch
Density: 1 gram per cubic centimeter (cc) at 39.2°F, 0.95865 gram per cc at 212°F