Question

An Erlenmeyer flask contains 25.00 mL of 0.500 M HCl before a titration is begun. How many moles of hydrogen ions are present in the flask at this time?

0.0125
12.5
20.0
50.0

Answer 1

0.0125 mol.

Step-by-step explanation:

Molarity of a solution is the no. of moles of a solute per 1.0 L of the solution.

M of HCl = 0.5 mol/L.

V = 25.0 mL = 0.025 L.

∴ no. of moles of HCl present in the flask at this time = MV = (0.5 mol/L)(0.025 L) = 0.0125 mol.