Concept explainers
“Hard” water has a high concentration of calcium and magnesium ions. Focusing on the calcium ion, a common home water -softening process is based on a reversible chemical change that can be expressed by
Zeolite ions are used in home water softners because they have a porous but rigid structure that is weakly attracted to cations, readily allowing an exchange among different ions.
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- Because calcium carbonate is a sink for CO32- in a lake, the student in Exercise 12.39 decides to go a step further and examine the equilibrium between carbonate ion and CaCOj. The reaction is Ca2+(aq) + COj2_(aq) ** CaCO,(s) The equilibrium constant for this reaction is 2.1 X 10*. If the initial calcium ion concentration is 0.02 AI and the carbonate concentration is 0.03 AI, what are the equilibrium concentrations of the ions? A student is simulating the carbonic acid—hydrogen carbonate equilibrium in a lake: H2COj(aq) H+(aq) + HCO}‘(aq) K = 4.4 X 10"7 She starts with 0.1000 AI carbonic acid. What are the concentrations of all species at equilibrium?arrow_forwardCalculate the value of the equilibrium constant for the reaction N2(g)+2O2(g)2NO2(g) if the concentrations of the species at equilibrium are [N2] = 0.0013, [O2] = 0.0024, and [NO2] = 0.00065.arrow_forwardWrite an equation for an equilibrium system that would lead to the following expressions (ac) for K. (a) K=(Pco)2 (PH2)5(PC2H6)(PH2O)2 (b) K=(PNH3)4 (PO2)5(PNO)4 (PH2O)6 (c) K=[ ClO3 ]2 [ Mn2+ ]2(Pcl2)[ MNO4 ]2 [ H+ ]4 ; liquid water is a productarrow_forward
- What is the law of mass action? Is it true that the value of K depends on the amounts of reactants and products mixed together initially? Explain. Is it true that reactions with large equilibrium constant values are very fast? Explain. There is only one value of the equilibrium constant for a particular system at a particular temperature, but there is an infinite number of equilibrium positions. Explain.arrow_forwardUse the solubility product constant from Appendix F to determine whether a precipitate will form if 10.0 mL of 1.0 106 M iron(II) chloride is added to 20.0 mL of 3.0 104 M barium hydroxide.arrow_forwardSome barium chloride is added to a solution that contains both K2SO4 (0.050 M) and Na3PO4 (0.020 M). (a) Which begins to precipitate first: the barium sulfate or the barium phosphate? (b) The concentration of the first anion species to precipitate, either the sulfate or phosphate, decreases as the precipitate forms. What is the concentration of the first species when the second begins to precipitate?arrow_forward
- In a particular experiment, the equilibrium constant measured for the reaction, Cl2(g)+NO2(g)Cl2NO2(g), is 2.8. Based on this measurement, calculate AG° for this reaction. Calculate AG° using data from Appendix E at the back of the book and discuss the agreement between your two calculations.arrow_forwardWrite the equilibrium constant expression for each of the following reactions in terms of concentrations. (a) CO2(g) + C(s) 2 CO(g) (b) [Cu(NH3)4)2+(aq) Cu2+(aq) + 4 NH3(aq) (c) CH3CO2H(aq) + H2O() CH3CO2(aq) + H3O+(aq)arrow_forwardWrite the reaction quotient expression for the ionization of NH3 in water.arrow_forward
- The following question is taken from a Chemistry Advanced Placement Examination and is used with the permission of the Educational Testing Service. Solve the following problem: MgF2(s)Mg2+(aq)+2F(aq) In a saturated solution of MgF2 at 18 C, the concentration of Mg2+ is 1.21103M . The equilibrium is represented by the preceding equation. (a) Write the expression for the solubility-product constant, Ksp, and calculate its value at 18 C. (b) Calculate the equilibrium concentration of Mg2+ in 1.000 L of saturated MgF2 solution at 18 C to which 0.100 mol of solid KF has been added. The KF dissolves completely. Assume the volume change is negligible. (c) Predict whether a precipitate of MgF2 will form when 100.0 mL of a 3.00103 -M solution of Mg(NO3)2 is mixed with 200.0 mL of a .2.00103 -M solution of NaF at 18 C. Show the calculations to support your prediction.. (d) At 27 C the concentration of Mg2+ in a saturated solution of MgF2 is 1.17103M . Is the dissolving of MgF2 in water all endothermic or an exothermic process? Give an explanation to support your conclusion.arrow_forwardWrite equilibrium constant expressions for the following reactions. For gases, use either pressures or concentrations. (a) 2 H2O2(g) 2 H2O(g) + O2(g) (b) CO(g) + O2g CO2(g) (c) C(s) + CO2(g) 2 CO(g) (d) NiO(s) + CO(g) Ni(s) + CO2(g)arrow_forwardHow is the strength of an acid related to the position of its ionization equilibrium? Write the equations for the dissociation (ionization) of HCI, HNO3, and HClO4in water. Since all these acids are strong acids, what does this indicate about the basicity of the Cl-, NO3, and ClO4ions? Are aqueous solutions of NaCl, NaNO3, or NaClO4basic?arrow_forward
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