# Relationship specific heat and density

### thermodynamics - Is density proportional to specific heat capacity? - Physics Stack Exchange

In thermodynamics, the heat capacity at constant volume, C V {\displaystyle C_{V }} C_{{V}} where ρ is the density of the substance under the applicable conditions. The corresponding expression for the ratio of specific heat capacities . materials were markedly different from those of the unfiied resin. The relationship: thermal diffusivity = thermal conductivity/(specific heat X density), does not. In response to the comment by Donald Brugman, I created the following plot of specific heat versus density for a bunch of metals for which I.

You may have seen this for yourself if you've ever put a sealed glass container containing a mostly-watery food soup, soda, etc. With most other liquids, solidification—which occurs when the temperature drops and kinetic motion energy of molecules is reduced—allows molecules to pack more tightly than in liquid form, giving the solid a greater density than the liquid.

Water is an anomaly that is, a weird standout in its lower density as a solid. Left Crystal structure of ice, with water molecules held in a regular 3D structure by hydrogen bonds. Right Image of icebergs floating on the surface of the ocean. Because it is less dense, ice floats on the surface of liquid water, as we see for an iceberg or the ice cubes in a glass of iced tea.

In lakes and ponds, a layer of ice forms on top of the liquid water, creating an insulating barrier that protects the animals and plant life in the pond below from freezing.

Why is it harmful for living things to freeze? We can understand this by thinking back to the case of a bottle of soda pop cracking in the freezer.

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When a cell freezes, its watery contents expand and its membrane just like the soda bottle is broken into pieces. Heat capacity of water It takes a lot of heat to increase the temperature of liquid water because some of the heat must be used to break hydrogen bonds between the molecules. In other words, water has a high specific heat capacity, which is defined as the amount of heat needed to raise the temperature of one gram of a substance by one degree Celsius. Like in nutrition information?

### is density and specific heat inversely proportional? | Yahoo Answers

This calorie is similar to that one, but not exactly the same. Because of its high heat capacity, water can minimize changes in temperature. For instance, the specific heat capacity of water is about five times greater than that of sand.

The land cools faster than the sea once the sun goes down, and the slow-cooling water can release heat to nearby land during the night. Water is also used by warm-blooded animals to distribute heat through their bodies: Heat of vaporization of water Just as it takes a lot of heat to increase the temperature of liquid water, it also takes an unusual amount of heat to vaporize a given amount of water, because hydrogen bonds must be broken in order for the molecules to fly off as gas.

That is, water has a high heat of vaporization, the amount of energy needed to change one gram of a liquid substance to a gas at constant temperature. Note that some molecules of water — ones that happen to have high kinetic energy — will escape from the surface of the water even at lower temperatures.

• Relations between heat capacities
• Specific heat, heat of vaporization, and density of water
• Is density and specific heat inversely proportional?

As water molecules evaporate, the surface they evaporate from gets cooler, a process called evaporative cooling. This is because the molecules with the highest kinetic energy are lost to evaporation see the video on evaporative cooling for more info. Attribution and references Attribution: Volumetric heat capacities in polyatomic gases vary widely, however, since they are dependent largely on the number of atoms per molecule in the gas, which in turn determines the total number of atoms per volume in the gas.

In solids[ edit ] Since the bulk density of a solid chemical element is strongly related to its molar mass usually about 3 R per mole, as noted abovethere exists noticeable inverse correlation between a solid's density and its specific heat capacity on a per-mass basis. This is due to a very approximate tendency of atoms of most elements to be about the same size, despite much wider variations in density and atomic weight.

### Specific heat, heat of vaporization, and density of water (article) | Khan Academy

These two factors constancy of atomic volume and constancy of mole-specific heat capacity result in a good correlation between the volume of any given solid chemical element and its total heat capacity. Another way of stating this, is that the volume-specific heat capacity volumetric heat capacity of solid elements is roughly a constant. The molar volume of solid elements is very roughly constant, and even more reliably so also is the molar heat capacity for most solid substances.

These two factors determine the volumetric heat capacity, which as a bulk property may be striking in consistency. Since the volume-specific corollary of the Dulong-Petit specific heat capacity relationship requires that atoms of all elements take up on average the same volume in solids, there are many departures from it, with most of these due to variations in atomic size.

For instance, arsenicwhich is only The heat capacity ratios of the two substances closely follows the ratios of their molar volumes the ratios of numbers of atoms in the same volume of each substance ; the departure from the correlation to simple volumes in this case is due to lighter arsenic atoms being significantly more closely packed than antimony atoms, instead of similar size.

Thermal inertia[ edit ] Thermal inertia is a term commonly used for modelling heat transfers.