Question

1.

A.write a chemical equation which goes with the statement:

i) K_b= 4.3 X 10^-10 for aniline (C6H5NH2)

ii)K_b = 2.1 X 10^-4 for carbonate ion

B. K_b =1.3 X 10^-3 for C5H11N and k_b= 6.3 x 10^-5 for N(CH3)3

i) Which base is the stronger base in water

ii) For the same solute concentration, which base has the larger equilibrium OH- concentrations?How did you decide?

C. Reaction of amide ion (NH2^-), ethoxide ion (OCH2CH3-), methoxide ion (OCH3-), hydride ion (H-), or oxide ion (O^2-) with water gives hydroxide ion as one product , for each ion, the reaction goes to completion.

i) For each of these ions write a net ionic equation for the reaction of the ions with water.

ii) is a salt supplying one of these ions a strong base or a weak acid?Explain.

Answer 1

1.

A.)

i) K_b= 4.3 X 10^-10 for aniline (C6H5NH2)

C6H5NH2 + H2O ------------------------> C6H5NH3+   + OH-

ii)K_b = 2.1 X 10^-4 for carbonate ion

CO3-2 + H2O ----------------------> HCO3- + OH-

B. K_b =1.3 X 10^-3 for C5H11N and k_b= 6.3 x 10^-5 for N(CH3)3

C5H11N + H2O -------------------> C5H11NH+ + OH-

(CH3)3N + H2O --------------------> (CH3)3NH+   + OH-

i) Which base is the stronger base in water

C5H11N stronger base in water because its Kb value is nore than (CH3)3N

ii) For the same solute concentration, which base has the larger equilibrium OH- concentrations?

C5H11N has larger equilibrium OH- concentration because it gives more OH- ions , since it has larger Kb value

C. Reaction of amide ion (NH2^-), ethoxide ion (OCH2CH3-), methoxide ion (OCH3-), hydride ion (H-), or oxide ion (O^2-) with water gives hydroxide ion as one product , for each ion, the reaction goes to completion.

i) For each of these ions write a net ionic equation for the reaction of the ions with water.

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

CH3CH2O- + H2O ------------------> CH3CH2OH + OH-

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

H- + H2O -----------------> 2OH-

O-2 + H2O -------------> 2OH-

ii) is a salt supplying one of these ions a strong base or a weak acid?Explain.

these are supplied by weak acid. becuase these are all strong conjugate and these salts are storng base

note : all bolded are answers