The concentration of hydroxide ions in the antacid, milk of magnesia, is 5.3 × 10−4 M. Calculate the concentration of hydronium ions at 25°C.

1.89 × 10^-11 M

Explanation:

Recall that;

[H^+] [OH^-] = 1 × 10^-14

[H^+] = concentration of hydronium ions

[OH^-] = concentration of hydroxide ion

Where [OH^-] = 5.3 × 10−4 M

[H^+]= 1 × 10^-14/5.3 × 10−4

[H^+]= 1.89 × 10^-11 M