POH = 14 - pH
pOH = -log [OH-]
The molarity is calculated using the following rule:
molarity = number of moles of solvent / volume of solution (in liters)
We have the volume of solution = 250 ml = 0.25 liters and the molarity = 3 m
Substituting in the equation, we get:
3 = number of moles / 0.25
number of moles = 3 x 0.25 = 0.75 moles
Answer: 0.8541 grams of HCl will be required.
Explanation: Moles can be calculated by using the formula:

Given mass of
= 0.610 g
Molar mass of
= 78 g/mol

Number of moles of
= 0.0078 moles
The reaction between
and HCl is a type of neutralization reaction because here acid and base are reacting to form an salt and also releases water.
Chemical equation for the above reaction follows:

By Stoichiometry,
1 mole of
reacts with 3 moles of HCl
So, 0.0078 moles of
will react with
= 0.0234 moles
Mass of HCl is calculated by using the mole formula, we get
Molar mass of HCl = 36.5 g/mol
Putting values in the equation, we get
Mass of HCl required will be = 0.8541 grams