Question

b) Methoxide ion, CH3O , and amide ion, NH2 , are very strong bases commonly used in organic solvents. However, both bases are

Answer 1

Leveling effect is the ability of a solvent to influence the properties of acid or base. The strength of a strong base in a solvent depends on the acidity of the solvent.

CH3O- + H2O -------> CH3OH + OH-

NH2- + H2O --------> NH3 + OH-

NH3 + H2O ------> NH4+ + OH-

Therefore, both methoxide and amide ions react with water to hydroxyl ions and the properties of OH- ions are dominant over methoxide or amide ions.

d) The salts, NaB when dissolved in water,

NaB + H2O <------> NaOH + BH

let x be the amount of NaOH formed.

Kb = [NaOH][BH]/[NaB] => Kw/Ka = x2/(0.1-x)

approximation: since x << 0.1, 0.1-x ~0.1.

Clearly, a high value of x or [OH-] results when Ka is smaller.

pH = 14 - pOH. => 14 - (-log[OH-]), which means a high value of [OH-] leads to high pH

In summary, a salt of an acid with low Ka value produces high pH when dissolved in water.

Thus, sodium formate solution produces highest pH and sodium nitrite solution produces the lowest pH.

The calculated pH values are 8.07, 8.08, 8.37 for NaNO2, NaF and HCOONa respectively.