Strong & weak acid & bases questions

Assignment: Questions on Topic 8.4 : Strong & weak acids & bases

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i.  Explain why 25.0 cm3 of 1.00 x 10−2 mol dm−3 hydrochloric acid solution, HCl(aq), has a lower pH value than 25.0 cm3 of 1.00 x 10−2 mol dm−3 ethanoic acid solution, CH3COOH(aq).

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ii.  When an acid is neutralized by a base the ionic equation for the reaction taking place is:

H+(aq) + OH–(aq) → H2O(l)

Explain why both of the above solutions react completely with exactly 25.0 cm3 of 1.00 x 10−2 mol dm−3 sodium hydroxide solution, NaOH(aq).

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The equilibrium constant for the dissociation of ammonia, NH3, in water is 1.8 x 10−5.

i.   Write the equation for the dissociation of ammonia in water.

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ii.  Write the equilibrium expression for the dissociation of ammonia in water.

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iii. Describe how the electrical conductivity of an aqueous solution of ammonia differs to an aqueous solution of sodium hydroxide with the same concentration.

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The ethoxide ion, C2H5O−, is a stronger base than the hydroxide ion, OH−.
Deduce how the equilibrium constant for the dissociation of ethanol will differ to the dissociation of water at the same temperature.

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Sulfuric acid is often assumed to be a strong diprotic acid. In fact the equilibrium constant for the dissociation of H2SO4(aq) to form HSO4–(aq) and H+(aq) is 2.4 x 106 and the equilibrium constant for the dissociation of HSO4–(aq) to form SO42–(aq) and H+(aq) is 1.0 x 10−2.
Use this information to properly describe the strength of sulfuric acid.

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i.  Distinguish between the words “concentrated”, “corrosive” and “strong” when applied to an acid.

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ii. Distinguish between the words “dilute” and “weak” when applied to an alkali.

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iii. Explain why a dilute aqueous solution of a strong acid might be a better conductor of electricity than a concentrated aqueous solution of a weak acid.

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