In the first step, NH2CH2COOH (glycine) reacts with HCl to form the acid salt of glycine, x1.
The acid salt of glycine, x1, then reacts with NaOH in the second step to form glycine, x2.
Finally, glycine x2 can react with HCl again in the third step to form the acid salt of glycine once more, x3.
In the first step, NH2CH2COOH (glycine) reacts with HCl to form the acid salt of glycine, x1.
The acid salt of glycine, x1, then reacts with NaOH in the second step to form glycine, x2.
Finally, glycine x2 can react with HCl again in the third step to form the acid salt of glycine once more, x3.