The base-dissociation constant, Kb for an unknown base is 1.4 10-9. The acid-dissociation constant, Ka, for the conjugate ion is. A) 1.4 × 10-5 B) 10 x 10-7 C)7.1 10-6 D) 7.1 x 10-4 E) 1.4 x 10-23

D) 7.1 x 10-4

Explanation:

Kb = 1.4 x 10^-9

Ka = ?

Relationship between Ka and Kb is given by:

Ka x Kb = Kw

where Kw = ion product constant which relates the concentrations of acids/bases and their conjugates in a solution. The value of this constant is 1.0 × 10^-14

Ka = Kw / Kb

Ka = (1.0 × 10^-14) / (1.4 x 10^-9)

Ka = 0.7142 x 10^-5

Ka = 7.142 x 10^-4

Correct option is D.

definition

                    entropy is a measure of the randomness or the extent of disorder of a chemical process.

                      enthalpy is a measure of the heat change of a reaction occurring at a constant pressure.

measurement units:

                        entropy is measured in joule per kelvin (jk⁻¹)   whereas enthalpy is measured in joule per mole (jmol⁻¹)

requirements:

                            entropy has no requirements or limits, and its change is measured by the division between the heat change of the chemical process and the temperature.

                              in contrast, enthalpy can only be related to the heat change of the reaction under standard conditions.

the formula mass of a molecule or a compound is the sum of the atomic weights of the atoms in its empirical formula

(that's what i know about formula mass)