To how much water should 250 mL of 12 M hydrochloric acid be added to
produce a 4.0 M solution?

500ml water

Explanation:

Molarity x Volume in liters (concentrated soln) = Molarity x Volume (diluted soln) ∴

250ml X 12M HCl =  4M x Volume of diluted solution

=> Volume of diluted solution = (250ml)(12M)/(4m) = 750 ml final solution vol. after mixing.

So the amount of water added to the 250ml of 12M acid = 750ml - 250ml = 500ml of water.

solute : a solute is a substance that is dissolved in another substance is known as a solvent. it is mixed with a special mixture know as homogeneous mixture.

solvent: a solvent is a substance that dissolved a solute, which results in a solution is known as solvent.