# Weak Acids, Weak Bases, and Salts

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What happens when strong acid or strong base is dissolved in water?
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It completely dissociates into ions
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What happens to the concentration of ions after strong acids/bases have been dissolved?
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concentration of hydronium ions is equal to the concentration of the strong acid; or the concentration of hydroxide ions is equal to the concentration of the strong base
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Logarithmic Scale of pH is what? and What ions does it involve?
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Involves the concentration of hydronium ions and are expressed on the logarithmic scale of pH: pH= -log[H3O+]
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How is OH- related to H3O+?
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By the ion product of water Kw which has a value of: Kw= [H3O+][OH-]= 1.0 x 10^-14
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What is pOH?
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-log[OH]-
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What is the relationship between pH and pOH?
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-log[H3O+]-log [OH-] = +14.00 so Pkw = pH + pOH = 14 and now if one of these is known the other three may be calculated using the previous three formulas
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What happens when weak acids and bases are put into a solution?
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they do not dissociate completely; react with water to ionize only partly and try to reach a state of equilibrium
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Equilibrium constants for Weak Acids and Weak Bases incomplete dissociation is called:
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dissociation or ionisation constants which have a definite value at a specific temperature, depending on whether the reactant is a base or acid they are called acid ionization constants and base ionization constants, respectively
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What happens to soluble salts when they dissolve in water?
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they dissociate completely into their ions but the fate of these ions depends on the acid or base from which they are derived
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What happens to strong acid anions and strong base cations when they are dissolved in water?
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they are simply hydrated- surrounded by water molecules
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What happens to the anions and cations of weak acids and bases?
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they react with water in a process called hydrolysis
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Hydrolysis
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the process in which anions and cations of weak acids and bases reacts with water
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What is necessary to determining the values of Ka and Kb for a weak conjugate acid-base pair?
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the pH and concentration of a salt
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Method I; Using indicators
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Obtain 200 mL of distilled water and boil to remove CO2; Rinse test tubes and rinse with 2mL of solution to be tested then add 5mL of solution into each test tube; add 3 or 4 drops of indicators to test tube, record color
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Method 2: pH Determination using pH paper
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pH paper has indicator and two types of readings are produced, wide-range and short range; wide range covers nearly whole scale,e short range covers colors within a certain range; test pH of a solution using wide-range then use short range to obtain a more exact pH; boil off CO2 from distilled water; gently arrange pH paper and clean a stirring rod and touch wet stirring rod with solution to wide range pH paper than use the appropriate short-range pH paper once it is determined which range it approximately falls into
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Method 3: Determination of pH with a pH meter
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set temperatur ecompensation dial to temperature of solution; immerse electrodes in liquid; calibrate meter with buffer solutions; rinse electrodes with Co2 free distilled water from a wash bottle between determinations; do not bump glass electrodes on bottom or side of container because they are fragile, record pH in notebook to nearest 0.01 pH unit
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Determine pH of Solutions for
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Sodium Chloride, Sodium Acetate, Sodium Sulfate, Sodium Bisulfate, Sodium Carbonate, Ammonium Chloride, and Ammonium Acetate
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How to dispose?
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Mix it all together and neutralize with 1 m HCL or 1 M NaOH and flush salt down sink with water
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Determine pH of what three solutes at what concentrations?
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Acetic Acid, Ammonia, Hydrochloric Acidl do not leave electrodes immersed in ammonia; only leave electrodes in solution long enough to determine pH, raise and rinse and store them in 7 pH buffer pr dotslled water
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What could happen to the electrodes in basic solutions?
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The basic solutions chemically attack the glass of the electrode.

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