# Density and temperature relationship formula

### How temperature is related to density? - Quora Density and specific volume of a liquid versus change in pressure and temperature. The density of a liquid will change with temperature and pressure. . An introduction to density, specific gravity and specific weight - formulas with examples. A set of fitted polynomial equations for calculating the physical variables density, entropy, heat capacity and potential temperature of a thermal saline fluid for a. If density is directly proportionate to pressure and inversely proportionate to The equation of state defines the relationship between pressure.

Pure Water Density of pure water zero salinity is directly proportional to pressure P and inversely proportional to temperature for temperatures T greater than or equal to 4 C ; i. We will discuss later the significance of the temperature of 4 C.

## Saturated Liquid Density

Why does an increase in temperature decrease density? Suppose you filled a balloon with air in a cold room and tied it shut so that there could be no change in the mass of air in the balloonthen walked outside into the sun, where the ballon was heated. The temperature increase would increase the volume of the gas in the balloon. Since density is inversely proportional to volume, this increase in volume would result in a decrease in density or you can think about this expansion allowing the gas molecules to be farther apart.

Why does density increase with increased pressure?

### Temperature Effects on Density | Sciencing

Suppose you filled a cylinder with liquid and inserted a piston to fix the amount of mass in the cylinder. Then you 'pushed down' on the piston increasing the pressure in the fluid. This increase in pressure would decrease the volume, and with the same reasoning as above, therefore, increase the density - or you can think about this pressure forcing the liquid molecules closer together.

Sea Water The density of sea water has the same pressure and temperature relationships as fresh water but, with the addition of "salt", its mass is increased, so the density of seawater also is directly proportional to salinity S ; i.

Note that there are an infinite number of combinations of temperature and salinity that will give the same value of density. Let's look at the density of water at 25 deg C and compare that to a higher temperature, 80 deg C. The density decreases from 0. This makes sense because, as heat is added to the liquid water, there is greater kinetic energy of the molecules and there are also more vibrations of the water molecules. Together these mean that each H2O unit in liquid water takes up more space as the temperature increases. We see the same trend in going from liquid water at 25 deg C 0.

Density increase as the temperature decreases. Below 4 deg C, however, the density decreases again. How can we explain this?

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Remember that liquid water and solid water have the same network of bonds. Liquid water at 25 deg is so rapidly breaking bonds between H2O units and reforming them that extra water molecules get trapped inside the water lattice. This is the reason why liquid water is more dense than solid water. The bonds in water break more slowly as temperature decreases and the structure tend to trap fewer extra water molecules.

### Pressure/Density/Temperature relationship - ATP Forum

At low temperature, more of the water has the same lattice as ice. Wikipedia, Water Density It is possible to have liquid water at temperatures well below 0 deg C. Molecules in this supercooled water are free to move.