Calcium hypochlorite [Ca(OCl)2] is used as a disinfectant for swimming pools. When dissolved in water it produces hypochlorous acid:
which ionizes as follows:
As strong oxidizing agents, both HClO and ClO− can kill bacteria by destroying their cellular components. However, too high a HClO concentration is irritating to the eyes of swimmers and too high a concentration of ClO− will cause the ions to decompose in sunlight. The recommended pH for pool water is 7.8. Calculate the percent of these species present at this pH.
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Chemistry
- For conjugate acidbase pairs, how are Ka and Kb related? Consider the reaction of acetic acid in water CH3CO2H(aq)+H2O(l)CH3CO2(aq)+H3O+(aq) where Ka = 1.8 105 a. Which two bases are competing for the proton? b. Which is the stronger base? c. In light of your answer to part b. why do we classify the acetate ion (CH3CO2) as a weak base? Use an appropriate reaction to justify your answer. In general, as base strength increases, conjugate acid strength decreases. Explain why the conjugate acid of the weak base NH3 is a weak acid. To summarize, the conjugate base of a weak acid is a weak base and the conjugate acid of a weak base is a weak acid (weak gives you weak). Assuming Ka for a monoprotic strong acid is 1 106, calculate Kb for the conjugate base of this strong acid. Why do conjugate bases of strong acids have no basic properties in water? List the conjugate bases of the six common strong acids. To tie it all together, some instructors have students think of Li+, K+, Rb+, Cs+, Ca2+, Sr2+, and Ba2+ as the conjugate acids of the strong bases LiOH, KOH. RbOH, CsOH, Ca(OH)2, Sr(OH)2, and Ba(OH)2. Although not technically correct, the conjugate acid strength of these cations is similar to the conjugate base strength of the strong acids. That is, these cations have no acidic properties in water; similarly, the conjugate bases of strong acids have no basic properties (strong gives you worthless). Fill in the blanks with the correct response. The conjugate base of a weak acid is a_____base. The conjugate acid of a weak base is a_____acid. The conjugate base of a strong acid is a_____base. The conjugate acid of a strong base is a_____ acid. (Hint: Weak gives you weak and strong gives you worthless.)arrow_forwardIonization of the first proton from H2SO4 is complete (H2SO4 is a strong acid); the acid-ionization constant for the second proton is 1.1 102. a What would be the approximate hydronium-ion concentration in 0.100 M H2SO4 if ionization of the second proton were ignored? b The ionization of the second proton must be considered for a more exact answer, however. Calculate the hydronium-ion concentration in 0.100 M H2SO4, accounting for the ionization of both protons.arrow_forwardProve that Ka3 Kb1 = Kw for phosphoric acid, H3PO4, by adding the chemical equilibrium expressions that corresponds to the third ionization step of the acid in water with the first of the three successive steps of the reaction of phosphate ion, PO43, with water.arrow_forward
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- At 50°C and 1 atm, K(w)=5.19X10⁻¹⁴. At these conditions,find (a) [H₃O⁺] in pure water, (b) [H₃O⁺] in 0.010 M NaOH,and (c) [OH] in 0.0010 M HClO₄. (d) Find [H₃O⁺] in 0.0100 M KOH at 100°C and 1000 atm (K(w)=1.10X10⁻¹²). (e) Find the pH of pure water at 100°C and 1000 atm.arrow_forwardThe concentration of H2S in a saturated aqueous solution at room temperature is approximately 0.1 M. Calculate [H3 O+], [HS−], and [S2−] in the solution:H2 S(aq) + H2 O(l) ⇌ H3 O+(aq) + HS−(aq) Ka1 = 8.9 × 10−8HS−(aq) + H2 O(l) ⇌ H3 O+(aq) + S2−(aq) Ka2 = 1.0 × 10−19arrow_forwardAt 25 oC, Ammonia is a weak base that reacts with water according to this equation: NH3(aq) + H2O(aq) ⇌ NH4+(aq) + OH−(aq) Briefly explain how the equilibrium will shift (to get back to equilibrium) if the following perturbations are made to the system: (a) Addition of HCl (b) Addition of NaOH (c) Addition of NH4Clarrow_forward
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