Inhibition Behaviour of Some Isonicotinic Acid Hydrazides on the Corrosion of Mild Steel in Hydrochloric Acid Solution

Table 2

Activation parameters for MS in 0.5 M HCl medium in the absence and presence of INIMH and INPMH at 500 ppm.

Inhibitor	Concentration (ppm)	𝐸𝑎 (kJ mol^−1)	𝑘 (mg cm^−2 h^−1)	Δ𝐻𝑎 (kJ mol^−1)	Δ𝐻𝑎=𝐸𝑎−𝑅𝑇 (kJ mol^−1)	Δ𝑆𝑎 (J mol^−1 K^−1)
Blank	0	19.003	1374.041	16.365	16.484	−197.574
INIMH	200	23.455	2570.396	20.813	20.936	−188.498
	300	24.355	3076.096	21.713	21.836	−187.005
	400	26.748	5357.966	24.106	24.229	−182.391
	500	27.457	5610.479	24.815	24.937	−182.027
INPMH	200	23.282	2483.133	20.659	20.763	−188.785
	300	24.087	2890.679	21.464	21.568	−187.522
	400	26.519	5128.613	23.876	23.999	−182.754
	500	27.093	5211.947	24.470	24.574	−182.620