Calculate the Ka for a 0.3 M solution of HA (unknown weak acid) if the pH = 3.65. The reaction can be modelled as HA (aq) + H2O (l) ←→ A- (aq) + H3O+ (aq).

The Ka : 1.671 x 10⁻⁷

Given

Reaction

HA (aq) + H2O (l) ←→ A- (aq) + H3O+ (aq).

0.3 M HA

pH = 3.65

Required

Ka

Solution

pH = - log [H3O+]

ICE method :

HA (aq)        ←→   A- (aq)    +    H3O+ (aq).

0.3                           0                 0

2.239.10⁻⁴           2.239.10⁻⁴   2.239.10⁻⁴

0.3-2.239.10⁻⁴    2.239.10⁻⁴    2.239.10⁻⁴

the number of protons in the nucleus of a given element. has slight luster and conducts electricity at high temperatures like metal.but like a nonmetal,boron is brittle and does not conduct electricity well at low temperatures. in graphite, carbon is a soft,brittle solid.it is reflective,ductile,or malleable.

each chemical family is represented as a group or column on the periodic table. based on chemical properties, there are 6 types of chemical families. group 1 represents alkali metals, group 2 represents alkaline earth metals, groups 3 to 12 represent transition metals, groups 13 to 16 represent non-metals and other metals, group 17 represents halogens and group 18 represents noble gases.