If the concentrations of calcium and carbonate ions in the mixture do not yield a reaction quotient, Q sp, that exceeds the solubility product, K sp, then no precipitation will occur. Consider, for example, mixing aqueous solutions of the soluble compounds sodium carbonate and calcium nitrate. It is important to realize that this equilibrium is established in any aqueous solution containing Ca 2+ and CO 3 2– ions, not just in a solution formed by saturating water with calcium carbonate. Solution ( a ) AgI ( s ) ⇌ Ag + ( a q ) + I − ( a q ) K sp = ( b ) CaCO 3 ( s ) ⇌ Ca 2+ ( a q ) + CO 3 2− ( a q ) K sp = ( c ) Mg ( OH ) 2 ( s ) ⇌ Mg 2+ ( a q ) + 2OH − ( a q ) K sp = 2 ( d ) Mg ( NH 4 ) PO 4 ( s ) ⇌ Mg 2+ ( a q ) + NH 4 + ( a q ) + PO 4 3− ( a q ) K sp = ( e ) Ca 5 ( PO 4 ) 3 OH ( s ) ⇌ 5Ca 2+ ( a q ) + 3PO 4 3− ( a q ) + OH − ( a q ) K sp = 5 3 ( a ) AgI ( s ) ⇌ Ag + ( a q ) + I − ( a q ) K sp = ( b ) CaCO 3 ( s ) ⇌ Ca 2+ ( a q ) + CO 3 2− ( a q ) K sp = ( c ) Mg ( OH ) 2 ( s ) ⇌ Mg 2+ ( a q ) + 2OH − ( a q ) K sp = 2 ( d ) Mg ( NH 4 ) PO 4 ( s ) ⇌ Mg 2+ ( a q ) + NH 4 + ( a q ) + PO 4 3− ( a q ) K sp = ( e ) Ca 5 ( PO 4 ) 3 OH ( s ) ⇌ 5Ca 2+ ( a q ) + 3PO 4 3− ( a q ) + OH − ( a q ) K sp = 5 3 Ĭheck Your LearningWrite the dissolution equation and the solubility product for each of the following slightly soluble compounds:ĬaCO 3 ( s ) ⇌ Ca 2+ ( a q ) + CO 3 2− ( a q ) K s p = 8.7 × 10 − 9 CaCO 3 ( s ) ⇌ Ca 2+ ( a q ) + CO 3 2− ( a q ) K s p = 8.7 × 10 − 9 (e) Ca 5(PO 4) 3OH, the mineral apatite, a source of phosphate for fertilizers (d) Mg(NH 4)PO 4, magnesium ammonium phosphate, an essentially insoluble substance used in tests for magnesium (c) Mg(OH) 2, magnesium hydroxide, the active ingredient in Milk of Magnesia (b) CaCO 3, calcium carbonate, the active ingredient in many over-the-counter chewable antacids (a) AgI, silver iodide, a solid with antiseptic properties Write the dissolution equation and the solubility product expression for each of the following slightly soluble ionic compounds: Writing Equations and Solubility Products For example, a saturated solution of silver chloride is one in which the equilibrium shown below has been established. A solute with finite solubility can yield a saturated solution when it is added to a solvent in an amount exceeding its solubility, resulting in a heterogeneous mixture of the saturated solution and the excess, undissolved solute. Recall from the chapter on solutions that the solubility of a substance can vary from essentially zero ( insoluble or sparingly soluble) to infinity ( miscible). This section applies previously introduced equilibrium concepts and tools to systems involving dissolution and precipitation. An understanding of the factors affecting compound solubility is, therefore, essential to the effective management of these processes. These equilibria underlie many natural and technological processes, ranging from tooth decay to water purification. Solubility equilibria are established when the dissolution and precipitation of a solute species occur at equal rates. Carry out equilibrium computations involving solubility, equilibrium expressions, and solute concentrations.Write chemical equations and equilibrium expressions representing solubility equilibria.So of course H2CO3 changes into carbon dioxide and water… but why? you can read a really interesting here to find out! It is pretty mind-boggling haha.Ĭredits to the following webpages:, chemistryland.By the end of this section, you will be able to: The picture above shows you that carbonic acid is H2CO3, it has 2H, 1C, and 3Os and how it is formed, umm the picture also shows a precipitation reaction btw, because calcium carbonate is insoluble and it will sort of precipitates out of solution by linking up with other calcium carbonate to form clumps.Īnyway, the key idea above for the baking soda reaction is that the real part of an acid that gives it acidic properties, which is the H+ ion is the one THAT REALLY REACTS at all, so the H+ ion reacts with the part of bicarbonate that is gives it basic properties which is actually the HCO3 to form voila! H2CO3 The carbonic acid decomposes to water and carbon dioxide gas. When water is added, the acid and bicarbonate combine to make a salt and carbonic acid. Baking powder is a mixture of acetic acid and baking soda. YEAH! acid and bases may sound like martians or other kind of aliens, but hey look at this, it is inolved in the baking of everyday’s good old bread!īaking soda is sodium bicarbonate.
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