Why is the thermal conductivity of a liquid larger than that of a gas?

Increased molecular collisions increase the exchange of energy between molecules. In liquids, molecules are relatively more closely packed than in gases. Therefore, the thermal conductivity of liquids predominantly depends on molecular diffusion effect, meaning the random movement of molecules.

When a solid is heated what happens to its volume?

All three states of matter (solid, liquid and gas) expand when heated. The atoms themselves do not expand, but the volume they take up does. When a solid is heated, its atoms vibrate faster about their fixed points. The relative increase in the size of solids when heated is therefore small.

How does the volume affect heat transfer?

The heat transfer rate from the water increases with the increase in the volume of drinking water. This is due to the increase in the water mass. Increasing the drinking water volume elevates the water mass; therefore it raises the heat transfer rate from the drinking water.

Why is thermal conductivity of solid larger than liquid?

Why is the thermal conductivity of a solid generally larger than that of a liquid? Since the intermolecular spacing is much larger and the motion of the molecules is more random for the fluid state than for the solid state, thermal energy transport is less effective.

Why does thermal conductivity increase with increasing temperature?

For water below 130C, as the temperature increases, water molecules exist as a cluster due to hydrogen bonds, so instead of each molecules being further apart, collision velocity increases. Thus, higher thermal conductivity.

What happens to the mass of most solids as their temperature increases?

When a substance is heated its volume increases and so the density decreases. In solids, increase in volume is negligible and hence decrease in density too. In liquids and gases, as the temperature increases, volume increases and therefore density decreases considerably.

Why do solids expand when heated?

When the solid is heated, the heat which is also a form of energy is gained by the atoms of the solids and this heat energy is transferred to adjacent atoms of the solids by the neighboring atoms. Hence, the solids on heating expands due to increase in kinetic energy of the atoms.

How does thermal conductivity affect heat transfer?

Thermal conductivity values are numerical values that are determined by experiment. The higher that the value is for a particular material, the more rapidly that heat will be transferred through that material. Materials with relatively high thermal conductivities are referred to as thermal conductors.

What is the relationship between thermal conductivity and the rate of heat transfer?

So the rate of heat transfer to an object is equal to the thermal conductivity of the material the object is made from, multiplied by the surface area in contact, multiplied by the difference in temperature between the two objects, divided by the thickness of the material.

Does the thermal conductivity of a gas vary with pressure?

As most solids and liquids are incompressible in nature, thermal conductivity does not vary with pressure. In case of gases, the kinetic theory of gases predicts and experiments confirm that the thermal conductivity of gases is proportional to the square root of the temperature T, and inversely proportional to the square root of the molar mass M.

How does particle density affect the mean free path of thermal conductivity?

In this case the mean free path is no longer dependent on the particle density: l≈δ=constant. With the mean free path as a constant, equation ( 9) then indicates a reduction of the thermal conductivity with decreasing particle density (or pressure)!

Which material has the highest hardness and thermal conductivity?

In particular, diamond has the highest hardness and thermal conductivity (k = 1000 W/m.K) of any bulk material. Most of PWRs use the uranium fuel, which is in the form of uranium dioxide.

How is thermal conductivity related to lattice vibrations?

As we have seen above, the conduction of heat through solids is dependent on two effects, namely lattice vibrations and flow of free electrons. The thermal conductivity is obtained by adding lattice and electronic components. = the thermal conductivity due to lattice vibrations = the thermal conductivity due to electronic effect