Working stressIt is the maximum permissible stress allowable for a structural member, the maximum safe valve forthe stress in the material of a practical structural member depends upon several factors.(i) It will depend upon the nature of the material(ii) It will also depend upon whether the stress is tensile, compressive or shear.It is defined as the ratio of shear stress to the shear strain and is denoted by G.Modulus of rigidity G = shear stressshear strainG = /QThe unit modulus of rigidity is N/mm2Poissons RatioIt is the ratio of transverse (lateral strain) to the corresponding axial (longitudinal strain resultingfrom uniformly distributed axial stress.A solution is formed when a solid, such as crystal of copper (ii) tetraoxosulphate (vi),dissolves in a liquid such as water to produce a homogeneous mixture. The solid is calledthe solute and the liquid the solventA suspension is a heterogeneous mixture of undissolved particle in a given medium. Theparticles are usually large enough to be seen without the acid of an instrument and theyeventually settle down if left standingSolubility is the property of a solid, liquid, or gaseous chemical substance called solute to dissolve in a solid, liquid, or gaseous solvent to form a solution of the solute in the solvent.Bulk ModulusIt is defined as the ratio of load to the volumetric strain and is denoted by K.K = loadVolumetric strainA saturated solution of a solute at a particular temperature is one which contains as muchsolute as it can dissolve at that temperature in the present of undissolved solute particularFactors that Affect SolubilitySolute-Solvent InteractionsThe relation between the solute and solvent is very important in determiningsolubility. Strong solute-solvent attractions equate to greatersolubilitywhile weak solute-solvent attractions equate to lessersolubility. In turn, polar solutes tend to dissolve best in polar solvents while non-polar solutes tend to dissolve best in non-polar solvents. In the case of a polar solute and non-polar solvent (or vice versa), it tends to be insoluble or only soluble to a miniscule degree. A general rule to remember is, "Like dissolves like."Common-Ion EffectThe common-ion effect is a term that describes the decrease insolubilityof an ionic compound when a salt that contains an ion that already exists in the chemical equilibrium is added to the mixture. This effect best be explained byLe Chtelier'sprinciple. Imagine ifthe slightly soluble ionic compound calcium sulfate,CaSO4, is added to water. The net ionic equation for the resulting chemical equilibrium is the following:CaSO4(s)Ca2+(aq)+SO24(aq)TemperatureTemperature changes affect the solubility of solids, liquids and gases differently. However, those effects are finitely determined only for solids and gases.SolidsThe effects of temperature on the solubility of solids differ depending on whether the reaction is endothermic or exothermic. UsingLe Chatelier'sprinciple,the effects of temperature in both scenarios can be determined.1. First, consider an endothermic reaction (heat is effectively on the reactantside with the solid). Increasing the temperature results in a stress on the reactants side from the additional heat.Le Chtelier'sprinciple predicts that the system shifts toward the product side in order to alleviate this stress. By shifting towards the productside, more of the solid is dissociated when equilibrium is again established, resulting inincreased solubility.2. Second, consider an exothermic reaction (heat is effectively on the productside with the dissociated ions). Increasing the temperature results in a stress on the products side from the additional heat.Le Chtelier'sprinciple predicts that the system shifts towardthe reactant side in order to alleviate this stress. By shifting towards the reactant's side, less of the solid is dissociated when equilibrium is again established, resulting in decreased solubility.LiquidsIn the case of liquids, there is no defined trends for the effects of temperature on the solubility of liquids.GasesIn understanding the effects of temperature on the solubility of gases, it is first important to remember that temperature is a measure of the average kinetic energy. As temperature increases, kinetic energy increases. in greater solubility.PressureThe effects of pressure are only significant in affecting the solubility of gases in liquids. Solids & Liquids: The effects of pressure changes on the solubility of solids and liquids are negligible. Gases: The effects of pressure on the solubility of gases in liquids can best be described through a combination ofHenry's lawandLe Chtelierprinciple. Henry's lawdictates thatwhen temperature is constant, the solubility of the gas corresponds to it's partial pressure. Consider the following formula of Henry's law:p=khcwhere: p is the partial pressure of the gas above the liquid, kh is Henry's law constant, and c is the concentrate of the gas in the liquid.