Butanoic acid, HC4H7O2, has a pKa value = 4.82. What is the value of the ionization constant for butanoic acid?

1.51 × 10⁻⁵

Explanation:

Step 1: Given data

pKa value: 4.82

Step 2: Write the reaction for the acid ionization of butanoic acid, HC₄H₇O₂

Butanoic acid is a weak acid that ionizes according to the following equation.

HC₄H₇O₂(aq) ⇄ C₄H₇O₂⁻(aq) + H⁺(aq)

The acid ionization constant for this reaction is Ka

Step 3: Calculate the value of the ionization constant for butanoic acid

We will use the following expression.

pKa = -log Ka

Ka = antilog -pKa = antilog -4.82 = 1.51 × 10⁻⁵

"among the transition metal elements, manganese and zinc have a slight lowering of electronegativities. the reason behind this is that the nuclear charges of these elements are slightly weaker than the other transition metal elements due to the way their valence electrons are filled up. both manganese and zinc have their valence electrons filled up to the 4th shell with 1 pair of electrons (4s2) completely occupying it. although the electrons in the 3rd shell (3d) are yet to be paired since the outer most shell is filled up, the ability of the nucleus to attract electrons is lessened. hence,   the electronegativity (or the ability to attract electrons) is lessened."