Borax is used in various household laundry and cleaning products,[23] including the "20 Mule Team Borax" laundry booster, "Boraxo" powdered hand soap, and some tooth bleaching formulas.[24]. When the saturated borax solution in the 150-mL beaker reaches about 10°C, stop stirring the solution and allow the borax crystals in the solution to settle. Borax is a boron-containing mineral that occurs in nature as a white powder composed of soft highly soluble crystals. [needs update], Review of the boron toxicity (as boric acid and borates) published 2012 in Journal of Toxicology and Environmental Health concluded: "It clearly appears that human B [boron] exposures, even in the highest exposed cohorts, are too low to reach the blood (and target tissue) concentrations that would be required to exert adverse effects on reproductive functions. [11], Borax was first discovered in dry lake beds in Tibet and was imported via the Silk Road to the Arabian Peninsula in the 8th century AD. Use Excel to create a graph of $$\ln K$$ versus $$1/T$$ for your data. If not add some more borax. [17][18], The English word borax is Latinized: the Middle English form was boras, from Old French boras, bourras. Does your value of $$\Delta H^{o}_{rxn}$$ suggest that the reaction for the dissolution of borax described by Equation \ref{5} is exothermic or endothermic? If you pour the hot borax solution into a cold graduated cylinder, the borax will precipitate in the cold cylinder. [55] If this recommendation is approved, all imports and uses of borax in the EU will have to be authorized by the ECHA. It is used to make buffer solutions in biochemistry, as a fire retardant, as an anti-fungal compound, in the manufacture of fiberglass, as a flux in metallurgy, neutron-capture shields for radioactive sources, a texturing agent in cooking, as a cross-linking agent in slime, as an alkali in photographic developers, as a precursor for other boron compounds, and is useful as an insecticide (similarly to boric acid). Fill this beaker to about the 75-mL mark with deionized water. Borax is replacing mercury as the preferred method for extracting gold in small-scale mining facilities. The most commonly encountered one is the octahydrate Na2H4B4O9•8H2O or [Na(H2O)+4]2 [B4O5(OH)2−4] (or Na2B4O7•10H2O, the "decahydrate", in the older notation). [17] It is poorly soluble in cold water, but its solubility increases significantly with temperature. Thus, $$K$$ in this experiment is the numeric but unitless value of $$K_{sp}$$. [28], A rubbery polymer sometimes called Slime, Flubber, 'gluep' or 'glurch' (or erroneously called Silly Putty, which is based on silicone polymers), can be made by cross-linking polyvinyl alcohol with borax. It is also used in the manufacture of the thermoresistant borosilicate glass commonly marketed as, "Pyrex."

3. Insert your thermometer into the solution.

Students must wear safety goggles at all times. where $$s$$ is the solubility of $$\ce{ Mg(OH)2}$$ (s) in moles per liter and $$2s$$ is the solubility of $$\ce{OH^{-}}$$ (aq). [9] It is a colorless crystalline solid that dissolves in water. Register now! In fact, the actual dissolution process for most substances is almost always more involved than that idealized by their $$K_{sp}$$ equilibrium expression. Ksp = [Na^+(aq)]^2[B4O5(OH)4^2-(aq)] The water and the solid are not included in the Ksp expression. The LibreTexts libraries are Powered by MindTouch® and are supported by the Department of Education Open Textbook Pilot Project, the UC Davis Office of the Provost, the UC Davis Library, the California State University Affordable Learning Solutions Program, and Merlot.