Answer to Question #129023 in General Chemistry for mike

Question

Our stomachs normally contain hydrochloric acid at a concentration of about 0.12M. Some foods increase stomach acidity which causes discomfort. There are a number of antacid tablets available commercially which ease this discomfort.

(i). What is the pH of the stomach juices under normal conditions?
(ii). What effect do the antacid tablets have on the pH of the stomach juices?
(iii). Some of these antacid tablets contain sodium hydrogen carbonate. Give an ionic equation in which the hydrogen carbonate ion is acting as a base.

Answer 1

(i) The neutral state of stomach juices under normal conditions range between $1.5$ and $3.5$

(ii) Antacids reduce acidity by neutralizing or counteracting the acid in the stomach, and reducing the amount of acid that is refluxed into the esophagus or emptied into the duodenum.

They also work by inhibiting the activity of pepsin enzyme produced in the stomach that is active only in an acid environment which is believed to damage the lining of the stomach, duodenum, and esophagus.

Anti acids thus raise the pH of stomach contents towards neutrality.

(iii) Ionic equations for the reaction.

$CO_3^{2-} {_{(aq)}}$ $+$ $H^+_{(aq)}\leftrightharpoons$ $HCO_3^-{_{(aq)}}$ $+H_2O_{(l)}$

$HCO_3^-{_{(aq)}}+H^+{_{(aq)}}\leftrightharpoons CO_2{_{(g)}}+H_2O{_{(l)}}$