Which Is The Connection Between The Particles Of A Substance And The Density Of The Substance

What affects the rate of diffusion of a substance?

Diffusion is the process by which atoms, molecules and other particles randomly blend together as a result of their kinetic energy. In general this leads to a phenomena where they move from an area of high concentration to an area of low concentration.Several factors that affect the rate of diffusion include temperature, density of the diffusing substance, medium of diffusion and concentration gradientTemperature : As temperature increases the average kinetic energy of particles increases. Greater kinetic energies lead to increased velocities. The increased velocity means that there is a greater chance of collisions between particles, resulting in an increased rate of diffusion. Generally, the rate of diffusion increases with temperature.Density of the Diffusing Substance : Density is defined as the amount of material that exists within a given volume. Regions of high density contain a greater number of particles per unit volume than regions of lower density. An increased number of particles leads to a greater chance of collisions, and this leads to an increased rate of diffusion. A lower number of particles leads to a reduced chance of collisions and this lowers the rate of diffusion. Therefore, high-density regions have a greater rate of diffusion than low-density regions.Medium of Diffusion : Diffusion also depends upon the medium in which it takes place. Physically, the particles within the medium act as a barrier to diffusion. Collisions between diffusing particles and the molecules of the medium lead to a reduction in the rate of diffusion. This means that the greater the number of molecules or larger particles within the medium, the lower the rate of diffusion.Concentration Gradient : The concentration of a substance is defined as the number of solute molecules that can be found within a given volume. Volumes of high concentration gradient have a large difference in the concentration of molecules over a unit length. A large difference in concentration leads to a greater probability of molecular collisions over the region and therefore increases the rate of diffusion. Generally, the greater the concentration gradient, the greater the rate of diffusion.

What is density of a substance?

The density, or more precisely, the volumetric mass density, of a substance is its mass per unit volume. The symbol most often used for density is ρ (the lower case Greek letter rho), although the Latin letter D can also be used. Mathematically, density is defined as mass divided by volumeAgraduated cylindercontaining various coloured liquids with different densities[math]{\displaystyle \rho ={\frac {m}{V}}}[/math]where ρ is the density, m is the mass, and V is the volume. In some cases (for instance, in the United States oil and gas industry), density is loosely defined as its weight per unit volume,[2]although this is scientifically inaccurate – this quantity is more specifically called specific weight.For a pure substance the density has the same numerical value as its mass concentration. Different materials usually have different densities, and density may be relevant to buoyancy, purity and packaging. Osmium and iridium are the densest known elements at standard conditions for temperature and pressure but certain chemical compounds may be denser.To simplify comparisons of density across different systems of units, it is sometimes replaced by the dimensionless quantity "relative density" or "specific gravity", i.e. the ratio of the density of the material to that of a standard material, usually water. Thus a relative density less than one means that the substance floats in water.The density of a material varies with temperature and pressure. This variation is typically small for solids and liquids but much greater for gases. Increasing the pressure on an object decreases the volume of the object and thus increases its density. Increasing the temperature of a substance (with a few exceptions) decreases its density by increasing its volume. In most materials, heating the bottom of a fluid results in convection of the heat from the bottom to the top, due to the decrease in the density of the heated fluid. This causes it to rise relative to more dense unheated material.The reciprocal of the density of a substance is occasionally called its specific volume, a term sometimes used in thermodynamics. Density is an intensive property in that increasing the amount of a substance does not increase its density; rather it increases its mass.

What are the factors that decide a given substance would be solid, liquid, or gas?

Then net effect of two opposing factors, the Intermolecular forces and Thermal energy would ddecide that the given substance would in be in solid liquid or gases.Intermolecular forces tend to keep the molecules/atoms/ions closer whereas thermal energy tends to keep them apart.At sufficiently low temperature, the thermal energy is low and intermolecular forces bring them so close that they cling to one another and occupies fix position. these can still oscilate about their mean positions and the substance exist in solid state.As thermal energy is high at higher temperatures. So, it keeps the molecules move farther away from each other. So density decreases and intermolecular forces are almost negligible (extremely weak) so the constituent particles are free to move about. Such substances exist in gaseous stateIn case of liquid state, the intermolecular forces of are not strong enough to bind the constituent particles and thermal energy is not so high to move them far away as in gases. The particles are close to each other but they can move around.

Is bulk density dependent on particle size?

I worked for seven years testing aggregate (gravel, crushed stone, and sand) for use in construction.If the particles were sieved so that all particles were almost the same size, bulk density would not be affected by particle size.However, in the real world, a particulate substance almost always has a range of particle sizes and bulk density is highly dependent upon what that range is. Smaller particles sift downward and fill up the spaces between larger particles. If your material has a lot of smaller particles, its bulk density will be higher than if it has few smaller particles.Bulk density also depends strongly on angularity. If particles are highly angular, the corners of particles tend to fit into the gaps between particles. If particles are well rounded, the gaps between particles tend to remain unfilled.Bulk density - WikipediaThis article discusses bulk density:Random close pack - Wikipedia

What is the relationship between bulk density and specific gravity?

Water is used to determine Specific Gravity. The density, or more precisely, the volumetric mass density, of a substance is its mass per unit volume. Density = Mass / Volume. Specific gravity is the density of a substance divided by the density of water. Since (at standard temperature and pressure) water has a density of 1 gram/cm3, and since all of the units cancel, specific gravity is usually very close to the same value as density (but without any units). Bulk density is a property of powders, granules, and other "divided" solids, especially used in reference to mineral components (soil, gravel), chemical substances, (pharmaceutical) ingredients, foodstuff, or any other masses of corpuscular or particulate matter. It is defined as the mass of many particles of the material divided by the total volume they occupy. So there is interstitial space considered with the "Bulk density" vs a "solid density" with no air pockets.

What is the difference between pure substances and mixtures in chemistry?

What they taught me in high school is that pure substances cannot be separated into other substances by physical means. For example common salt cannot be separated into constituents by physical means. You can separate it into individual crystals, but they are all the same sodium chloride substance, with the same properties. You could melt salt, or dissolve it and recrystallize it, but it is still salt. Molten salt can be electrolyzed to separate it into the sodium and chlorine elements that constitute it, but that is a chemical change.A mixture has two or more components that can be separated by physical means, like distillation. If you dissolve salt in water, it may look like a pure liquid, but once the water evaporates, you are left with a solid residue that is obviously different from the liquid it came from. That tells you that the liquid you saw before was a mixture. Other mixtures are easy to recognize as mixtures, as when you actually see particles with different appearance that you can separate and examine. For example, you could separate small and large particles from a mixture of salt and sugar. Both would readily dissolve in water, but the solutions would have different properties, so you would know the two kinds of particles represented different substances.Analytical chemists like me, twist the definitions a bit to make an exception for water. Many substances tend to absorb and/or retain moisture to various extents, so a substance such as “common salt” may contain a bit of water, and I would still consider it to be a pure substance. In fact the salt in your salt shaker may have gained some moisture, unless it contains some “anti-caking” additive.Now, what I call pure is just pure enough. My job involves finding impurities, and I have arrived at the conclusion that no substance is absolutely pure. If you cannot detect impurities it is probably because your analysis method is not sensitive enough.