Water Density & Volume: 0-100°C

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Discussion Overview

The discussion centers on the relationship between water density and volume as temperature changes from 0°C to 100°C. Participants explore the implications of density changes, volume expansion, and the mathematical relationships involved, including potential non-linearities.

Discussion Character

  • Debate/contested
  • Technical explanation
  • Mathematical reasoning

Main Points Raised

  • Some participants assert that water density at 0°C is approximately 990 kg/m³ and at 100°C is around 1030 kg/m³, leading to a perceived 4% decrease in mass for 1 m³ of water.
  • Others challenge these density values, stating that water is not denser at 100°C than at 0°C and reference external sources for clarification.
  • It is noted that the density-temperature relationship for liquid water is non-linear, with maximum density occurring around 4°C.
  • Some participants propose that the relationship between density decrease and volume increase may involve a square root relation, although this is contested.
  • One participant mentions that the expansion rate of water is approximately 1.0002 for each 1°C increase, but this is said to be true primarily around 20°C.
  • Another participant points out that the product of density and specific volume equals 1, suggesting no square root relationship exists.

Areas of Agreement / Disagreement

Participants express disagreement regarding the density values at different temperatures and the nature of the relationship between density decrease and volume increase. There is no consensus on the mathematical relationship or the accuracy of the initial claims.

Contextual Notes

Some claims depend on specific temperature ranges and may not hold universally. The discussion includes references to external data sources and the need for further calculations to clarify the relationships discussed.

Yuri B.
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Water density at 0 C is 990 kg/m3.
Water density at 100 C is 1030 kg/m3 - 1 m3 of water "loses" about 4 % of its mass.
Water expansion rate is 1.0002 for each 1 C increase in temperature - 2 % for the above rise from 0 C to 100 C..
How comes that water density decreases 4 % but its volume increases just 2 % ?
 
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Yuri B. said:
Water density at 0 C is 990 kg/m3.
Water density at 100 C is 1030 kg/m3 - 1 m3 of water "loses" about 4 % of its mass.
Water expansion rate is 1.0002 for each 1 C increase in temperature - 2 % for the above rise from 0 C to 100 C..
How comes that water density decreases 4 % but its volume increases just 2 % ?

It's one consequence of dealing with too little information. The density-temperature relation for liquid water between 0 C and 100 C is a curve, with the maximum density occurring at about 4 C. Plot the values from the density table referenced by DrClaude.
 
I mistakenly put it otherwise so, more precisely - according to the reference - it should be :
0.999808 at 0 °C
0.958593 at 100 °C - about 4 % of the initial value
But the volume will increase just 2 %
Maybe there is square root relation ?
 
Yuri B. said:
I mistakenly put it otherwise so, more precisely - according to the reference - it should be :
0.999808 at 0 °C
0.958593 at 100 °C - about 4 % of the initial value
But the volume will increase just 2 %
Maybe there is square root relation ?
Again: the relationship isn't linear.
 
Let it be it, but I refer to the exactly 2 points (on the "curve") between which there is the 4% decrease in density for, as it seems, 2% increase in volume
Square root ?
 
Yuri B. said:
Let it be it, but I refer to the exactly 2 points (on the "curve") between which there is the 4% decrease in density for, as it seems, 2% increase in volume
Square root ?
But as Russ said, the relationship is not linear. In other words, you can't use the same expansion coefficient at all temperatures.

Yuri B. said:
Water expansion rate is 1.0002 for each 1 C increase in temperature
This is only true around 20°C.
 
Please have a look at the link DrClaude gave you in post #2. You may even try dropping the data into a spreadsheet and calculating the coefficient at different temperatures. You will find that it varies substantially from 2%.
 
Last edited:
But will % of expansion = % of decrease in density ?
 
  • #10
The product of density and specific volume is 1. So there is no square root relation involved.

Chet
 
  • #11
Thank you.
 

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